DP Chemistry Questionbank

Identify the formula and state symbol of X.

Magnesium burns in air to form a white compound, magnesium oxide. Formulate an equation for the reaction of magnesium oxide with water.

Magnesium chloride can be electrolysed.

Deduce the half-equations for the reactions at each electrode when molten magnesium chloride is electrolysed, showing the state symbols of the products. The melting points of magnesium and magnesium chloride are 922 K and 987 K respectively.

Anode (positive electrode):

Cathode (negative electrode):

Magnesium chloride can be electrolysed.

(i) Deduce the half-equations for the reactions at each electrode when molten magnesium chloride is electrolysed, showing the state symbols of the products. The melting points of magnesium and magnesium chloride are 922K and 987K respectively.

(ii) Identify the type of reaction occurring at the cathode (negative electrode).

(iii) State the products when a very dilute aqueous solution of magnesium chloride is electrolysed.

Which statements about mixtures are correct?

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

Formulate an equation for this reaction.

Formulate an equation for the reaction between VO²⁺(aq) and V²⁺(aq) in acidic solution to form V³⁺(aq).

Formulate an equation for the reaction between VO²⁺(aq) and V²⁺(aq) in acidic solution to form V³⁺(aq).

What is the sum of the coefficients when the equation is balanced with whole numbers?

_—C₈H₁₈(g) + _—O₂(g) → _—CO(g) + _—H₂O(l)

A.     26.5

B.     30

C.     53

D.     61

What is the sum of the coefficients when the following equation is balanced using the smallest whole numbers?

__C₆H₁₂O₆ (aq) → __C₂H₅OH (aq) + __CO₂ (g)

A. 4

B. 5

C. 9

D. 10

The combustion of urea produces water, carbon dioxide and nitrogen.

Formulate a balanced equation for the reaction.

Outline why repeating quantitative measurements is important.

The combustion of urea produces water, carbon dioxide and nitrogen.

Formulate a balanced equation for the reaction.

Annotate the balanced equation below with state symbols.

CaCO₃(__) + 2HCl(__) → CaCl₂(__) + CO₂(__) + H₂O(__)

What is the sum of the coefficients when the equation is balanced with the lowest whole number ratio?

__Na₂S₂O₃(aq) + __HCl(aq) → __S(s) + __SO₂(g) + __NaCl(aq) + __H₂O(l)

A.     6

B.     7

C.     8

D.     9

Formulate the equation for the reaction of H₂SO₄ with Mg(OH)₂.

Formulate the equation for the complete combustion of benzoic acid in oxygen using only integer coefficients.

The reaction of sodium peroxide with excess water produces hydrogen peroxide and one other sodium compound. Suggest the formula of this compound.

Deduce, giving a reason, the group of elements in the periodic table most likely to undergo sublimation.

What is the sum of the integer coefficients when propene undergoes complete combustion?

__C₃H₆ (g) + __O₂ (g) → __CO₂ (g) + __H₂O (l)

A. 11

B. 17

C. 21

D. 23

Formulate the equation for the complete combustion of benzoic acid in oxygen using only integer coefficients.

The reaction of sodium peroxide with excess water produces hydrogen peroxide and one other sodium compound. Suggest the formula of this compound.

Deduce, giving a reason, the group of elements in the periodic table most likely to undergo sublimation.

What is the sum of the coefficients when the equation is balanced with the smallest whole numbers?

__BaCl₂ (aq) + __Fe₂(SO₄)₃ (aq) → __FeCl₃ (aq) + __BaSO₄ (s)

A. 4

B. 6

C. 8

D. 9

What is the sum of the integer coefficients when propene undergoes complete combustion?

__C₃H₆ (g) + __O₂ (g) → __CO₂ (g) + __H₂O (l)

A. 11

B. 17

C. 21

D. 23

Write an equation for the complete combustion of the compound C₃H₈O formed in (a)(iv).

Write the half-equation for the formation of gas bubbles at electrode 1.

Deduce the half-equation for the formation of the gas identified in (c)(iii).

Deduce the equation for the decomposition of guanidinium nitrate.

Another airbag reactant produces nitrogen gas and sodium.

Suggest, including an equation, why the products of this reactant present a safety hazard.

What is the sum of the coefficients when the equation is balanced with whole numbers?

__MnO₂ (s) + __HCl (aq) → __MnCl₂ (aq) + __H₂O (l) + __Cl₂ (g)

A.  6

B.  7

C.  8

D.  9

Write an equation for the reaction of C₂H₅Cl with aqueous sodium hydroxide to produce a C₂H₆O compound, showing structural formulas.

Write an equation for the complete combustion of the organic product in (b).

Write the half-equation for the formation of gas bubbles at electrode 1.

Write the equation for the reaction of chloroethane with a dilute aqueous solution of sodium hydroxide.

Write a balanced equation for the reaction.

Comment on the magnitudes of random and systematic errors in this experiment using the answers in (e).

What is the coefficient of $\text{HCl}$ (aq) when the equation is balanced using the smallest possible whole numbers?

$\text{\_\_CuO\hspace{0.05em}(s)+ \_\_HCl} {\text{(aq) → \_\_CuCl}}_{\text{2}} {\text{(aq) + \_\_H}}_{\text{2}}\text{O} \text{(l)}$

A.  1

B.  2

C.  3

D.  4

What is the sum of the coefficients when the equation is balanced with whole numbers?

__Sn(OH)₄(aq) + __NaOH (aq) → __Na₂SnO₃(aq) + __H₂O (l)

A.  4

B.  5

C.  6

D.  7

Write the equation for this reaction.

Determine the overall equation for the production of methanol.

Write the equation for this reaction.

Determine the overall equation for the production of methanol.

Write the equation for the reaction of Ca(OH)₂ (aq) with hydrochloric acid, HCl (aq).

Write the equation for the reaction of Ca(OH)₂(aq) with hydrochloric acid, HCl (aq).

Write the chemical equation for the complete combustion of ethanol.

Write an equation for the reaction of white phosphorus (P₄) with chlorine gas to form phosphorus trichloride (PCl₃).

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Write an equation for the reaction of white phosphorus (P₄) with chlorine gas to form phosphorus trichloride (PCl₃).

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Which equation represents the deposition of iodine?

A.  I₂(g) → I₂(l)

B.  I₂(g) → I₂(s)

C.  I₂(l) → I₂(g)

D.  I₂(s) → I₂(g)

Write a balanced equation for the reaction that occurs.

Calculate coefficients that balance the equation for the following reaction.

__ Mg₃N₂(s) + __ H₂O (l) → __ Mg(OH)₂(s) + __ NH₃(aq)

Write a balanced equation for the reaction that occurs.

Calculate coefficients that balance the equation for the following reaction.

Determine the coefficients that balance the equation for the reaction of lithium with water.

One possible product, X, of the reaction of ethane with chlorine has the following composition by mass:

carbon: 24.27%, hydrogen: 4.08%, chlorine: 71.65%

Determine the empirical formula of the product.

One possible product, X, of the reaction of ethane with chlorine has the following composition by mass:

carbon: 24.27%, hydrogen: 4.08%, chlorine: 71.65%

Determine the empirical formula of the product.

The sequence of nitrogenous bases in DNA determines hereditary characteristics.

Calculate the mole percentages of cytosine, guanine and thymine in a double helical DNA structure if it contains 17% adenine by mole.

How many moles of oxygen atoms are there in 0.500 mol of hydrated iron(II) ammonium sulfate, (NH₄)₂Fe(SO₄)₂•6H₂O(s)?

A.     4.00

B.     7.00

C.     8.00

D.     14.00

After heating 3.760 g of a silver oxide 3.275 g of silver remained. Determine the empirical formula of Ag_xO_y.

Calculate the molar mass of the acid.

How many atoms of nitrogen are there in 0.50 mol of (NH₄)₂CO₃?

A. 1

B. 2

C. 3.01 × 10²³

D. 6.02 × 10²³

What is the value of x when 32.2 g of Na₂SO₄•xH₂O are heated leaving 14.2 g of anhydrous Na₂SO₄? M_r(H₂O) = 18; M_r(Na₂SO₄) = 142.

Na₂SO_4•xH₂O (s) → Na₂SO₄ (s) + xH₂O (g)

A. 0.1

B. 1

C. 5

D. 10

How many grams of sodium azide, NaN₃, are needed to produce 68.1 dm³ of N₂ (g) at STP?

Molar volume at STP = 22.7 dm³ mol^–1; M_r(NaN₃) = 65.0

2NaN₃ (s) → 3N₂ (g) + 2Na (s)

A. 32.5

B. 65.0

C. 130.0

D. 195.0

Which solution neutralizes 50.0 cm³ of 0.120 mol dm^–3 NaOH (aq)?

A. 12.5 cm³ of 0.080 mol dm^–3 H₃PO₄

B. 25.0 cm³ of 0.120 mol dm^–3 CH₃COOH

C. 25.0 cm³ of 0.120 mol dm^–3 H₂SO₄

D. 50.0 cm³ of 0.060 mol dm^–3 HNO₃

Calculate the enthalpy change, ΔH, in kJ mol^–1, for the reaction between ethanoic acid and sodium hydroxide.

Complete combustion of 0.1595 g of menthol produces 0.4490 g of carbon dioxide and 0.1840 g of water. Determine the empirical formula of the compound showing your working.

Complete combustion of 0.1595 g of menthol produces 0.4490 g of carbon dioxide and 0.1840 g of water. Determine the empirical formula of the compound showing your working.

Determine the molecular formula of menthol using your answers from parts (d)(i) and (ii).

Calculate the percentage of water by mass in the NaCl•2H₂O crystals. Use the data from section 6 of the data booklet and give your answer to two decimal places.

Calculate the percentage by mass of nitrogen in urea to two decimal places using section 6 of the data booklet.

Calculate the percentage by mass of nitrogen in urea to two decimal places using section 6 of the data booklet.

The solution of palmitic acid had a concentration of 0.0034 mol dm⁻³. Calculate the number of molecules of palmitic acid present in the 0.050 cm³ drop, using section 2 of the data booklet.

Assuming the sudden change in gradient occurs at 240 cm², calculate the area, in cm², that a single molecule of palmitic acid occupies on surface of the water.

If you did not obtain an answer for (b)(ii) use a value of 8.2 × 10¹⁶, but this is not the correct answer.

Determine the mass of Mg(OH)₂ in the antacid tablet.

How many moles of FeS₂ are required to produce 32 g of SO₂? (A_r: S = 32, O = 16)

4FeS₂ (s) + 11O₂ (g) → 2Fe₂O₃ (s) + 8SO₂ (g)

A.   0.25

B.   0.50

C.   1.0

D.   2.0

16 g of bromine react with 5.2 g of metal, M, to form MBr₂. What is the relative atomic mass of the metal M? (A_r : Br = 80)

A.   13

B.   26

C.   52

D.   104

Determine the limiting reactant showing your working.

Determine the limiting reactant showing your working.

Calculate the number of hydrogen atoms in 1.00 g of propan-2-ol.

Determine the empirical formula of the compound, showing your working.

Sodium percarbonate, 2Na₂CO₃•3H₂O₂, is an adduct of sodium carbonate and hydrogen peroxide and is used as a cleaning agent.

M_r (2Na₂CO₃•3H₂O₂) = 314.04

Calculate the percentage by mass of hydrogen peroxide in sodium percarbonate, giving your answer to two decimal places.

A sample of gas was enriched to contain 2 % by mass of ¹⁵N with the remainder being ¹⁴N.

Calculate the relative molecular mass of the resulting N₂O.

Calculate the percentage, by mass, of rhenium in ReCl₃.

How many moles of magnesium hydroxide are produced with 0.50 mol of ammonia?

Mg₃N₂ (s) + 6H₂O (l) → 3Mg(OH)₂ (aq) + 2NH₃ (aq)

A. 0.25

B. 0.33

C. 0.75

D. 1.5

Sodium percarbonate, 2Na₂CO₃•3H₂O₂, is an adduct of sodium carbonate and hydrogen peroxide and is used as a cleaning agent.

M_r (2Na₂CO₃•3H₂O₂) = 314.04

Calculate the percentage by mass of hydrogen peroxide in sodium percarbonate, giving your answer to two decimal places.

A sample of gas was enriched to contain 2 % by mass of ¹⁵N with the remainder being ¹⁴N.

Calculate the relative molecular mass of the resulting N₂O.

Describe the characteristics of the nematic liquid crystal phase and the effect that an electric field has on it.

Shape of molecules:

Distribution:

Effect of electric field:

How many moles of magnesium hydroxide are produced with 0.50 mol of ammonia?

Mg₃N₂ (s) + 6H₂O (l) → 3Mg(OH)₂ (aq) + 2NH₃ (aq)

A. 0.25

B. 0.33

C. 0.75

D. 1.5

Calculate the number of moles of oxygen in the day 0 sample.

Calculate the total number of moles of gas produced from the decomposition of 10.0 g of guanidinium nitrate.

Which contains the greatest number of moles of oxygen atoms?

A.  0.05 mol Mg(NO₃)₂

B.  0.05 mol C₆H₄(NO₂)₂

C.  0.1 mol H₂O

D.  0.1 mol NO₂

What is the molar mass, in $\mathrm{g} {\mathrm{mol}}^{-1}$, of a compound if $0.200 \mathrm{mol}$ of the compound has a mass of $13.2 \mathrm{g}$?

A.  $66.0$

B.  $66$

C.  $26.4$

D.  $26$

What is the number of carbon atoms in $12 \mathrm{g}$ of ethanoic acid ${\mathrm{CH}}_3\mathrm{COOH}$, $M_{\mathrm{r}}=60$?

A.  $0.20$

B.  $2.0$

C.  $1.2\times {10}^{23}$

D.  $2.4\times {10}^{23}$

Which of these molecular formulae are also empirical formulae?

1.  ${\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}$
2.  ${\mathrm{C}}_2{\mathrm{H}}_4{\mathrm{O}}_2$
3.  ${\mathrm{C}}_5{\mathrm{H}}_{12}$

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

Calculate the percentage by mass of chlorine in ${\mathrm{CCl}}_2{\mathrm{F}}_2$.

Calculate the percentage by mass of chlorine in ${\mathrm{CCl}}_2{\mathrm{F}}_2$.

Consider the following antacids:

Show that antacid X is more effective, per tablet, than antacid Y.

What is the number of hydrogen atoms in 2.00 moles of Ca(HCO₃)₂?

Avogadro’s constant, L or N_A: 6.02 × 10²³ mol⁻¹

A.  2.00

B.  4.00

C.  1.20 × 10²⁴

D.  2.41 × 10²⁴

3.00 mol of C₃H₈ is mixed with 20.00 mol of O₂. Which quantity is present at the end of the reaction?

C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O (g)

A.  1.00 mol of C₃H₈

B.  5.00 mol of O₂

C.  12.00 mol of CO₂

D.  16.00 mol of H₂O

Determine the empirical formula of the compound using section 6 of the data booklet.

Determine the molecular formula of this compound if its molar mass is 88.12 g mol⁻¹. If you did not obtain an answer in (a) use CS, but this is not the correct answer.

Determine the empirical formula of the compound using section 6 of the data booklet.

Determine the molecular formula of this compound if its molar mass is 88.12 g mol⁻¹. If you did not obtain an answer in (a) use CS, but this is not the correct answer.

0.2 mol of sodium hydrogencarbonate is decomposed by heating until constant mass.

2 NaHCO₃(s) → Na₂CO₃ (s) + H₂O (g) + CO₂ (g)

How many moles of gas are produced?

A.  0.1

B.  0.2

C.  0.3

D.  0.4

2.67 g of lead (II) carbonate is decomposed by heating until constant mass.

PbCO₃(s) → PbO (s) + CO₂(g)

What is the final mass of solid?

A.  0.44 g

B.  2.23 g

C.  2.67 g

D.  3.11 g

0.02 mol of zinc is added to 10.0 cm³ of 1.0 mol dm^–3 hydrochloric acid.

Zn (s) + 2HCl (aq) → ZnCl₂(aq) + H₂(g)

How many moles of hydrogen are produced?

A.  0.005

B.  0.01

C.  0.02

D.  0.04

Calculate the amount of magnesium, in mol, that was used.

Calculate the amount of magnesium, in mol, that was used.

Which volume, in cm³, of 0.20 mol dm^-3 NaOH (aq) is needed to neutralize 0.050 mol of H₂S(g)? 

H₂S(g) + 2NaOH(aq) → Na₂S(aq) + 2H₂O(l) 

A. 0.25 
B. 0.50 
C. 250 
D. 500

The complete combustion of 15.0cm³ of a gaseous hydrocarbon X produces 60.0 cm³ of carbon dioxide gas and 75.0 cm³ of water vapour. What is the molecular formula of X? (All volumes are measured at the same temperature and pressure.) 

A. C₄H₆ 
B. C₄H₈ 
C. C₄H₁₀ 
D. C₆H₁₀ 

5.0mol of Fe₂O₃(s) and 6.0mol of CO(g) react according to the equation below. What is the limiting reactant and how many moles of the excess reactant remain unreacted?

Fe₂O₃(s) + 3CO(g) → 2Fe(s) + 3CO₂(g)

5.00 g of an impure sample of hydrated ethanedioic acid, (COOH)₂•2H₂O, was dissolved in water to make 1.00 dm³ of solution. 25.0 cm³ samples of this solution were titrated against a 0.100 mol dm^-3 solution of sodium hydroxide using a suitable indicator.

(COOH)₂ (aq) + 2NaOH (aq) → (COONa)₂ (aq) + 2H₂O (l)

The mean value of the titre was 14.0 cm³.

(i)   Calculate the amount, in mol, of NaOH in 14.0 cm³ of 0.100 mol dm^-3 solution.

(ii)  Calculate the amount, in mol, of ethanedioic acid in each 25.0 cm³ sample.

(iii) Determine the percentage purity of the hydrated ethanedioic acid sample.

The precipitate of sulfur makes the mixture cloudy, so a mark underneath the reaction mixture becomes invisible with time.

10.0 cm³ of 2.00 mol dm^-3 hydrochloric acid was added to a 50.0 cm³ solution of sodium thiosulfate at temperature, T1. Students measured the time taken for the mark to be no longer visible to the naked eye. The experiment was repeated at different concentrations of sodium thiosulfate.

Show that the hydrochloric acid added to the flask in experiment 1 is in excess.

5.00 g of an impure sample of hydrated ethanedioic acid, (COOH)₂•2H₂O, was dissolved in water to make 1.00 dm³ of solution. 25.0 cm³ samples of this solution were titrated against a 0.100 mol dm^-3 solution of sodium hydroxide using a suitable indicator.

(COOH)₂ (aq) + 2NaOH (aq) → (COONa)₂ (aq) + 2H₂O (l)

The mean value of the titre was 14.0 cm³.

(i) Suggest a suitable indicator for this titration. Use section 22 of the data booklet.

(ii) Calculate the amount, in mol, of NaOH in 14.0 cm³ of 0.100 mol dm^-3 solution.

(iii) Calculate the amount, in mol, of ethanedioic acid in each 25.0 cm³ sample.

(iv) Determine the percentage purity of the hydrated ethanedioic acid sample.

Determine the percentage experimental yield of the product after recrystallization. The molar masses are as follows: M(salicylic acid) = 138.13 g mol⁻¹, M(aspirin) = 180.17 g mol⁻¹. (You do not need to process the uncertainties in the calculation.)

5.0 cm³ of 2.00 mol$$dm^–3 sodium carbonate solution, Na₂CO₃(aq), was added to a volumetric flask and the volume was made up to 500 cm³ with water. What is the concentration, in mol$$dm^–3, of the solution?

A.     0.0050

B.     0.0040

C.     0.020

D.     0.010

What is the expression for the volume of hydrogen gas, in dm³, produced at STP when 0.30 g of magnesium reacts with excess hydrochloric acid solution?

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

Molar volume of an ideal gas at STP = 22.7 dm³$$mol⁻¹

A.     $\frac{0.30\times 2\times 22.7}{24.31}$

B.     $\frac{0.30\times 22.7}{24.31}$

C.     $\frac{0.30\times 24.31}{22.7}$

D.     $\frac{0.30\times 22.7}{24.31\times 2}$

Calculate, showing your working, the mass of hydrazine needed to remove all the dissolved oxygen from 1000 dm³ of the sample.

Calculate the volume, in dm³, of nitrogen formed under SATP conditions. (The volume of 1 mol of gas = 24.8 dm³ at SATP.)

Suggest how the end point of the titration might be estimated from the graph.

State and explain how the graph would differ if 1 mol$$dm⁻³ sulfuric acid had been used instead of 1 mol$$dm⁻³ hydrochloric acid.

What is the maximum volume, in dm³, of CO₂(g) produced when 1.00 g of CaCO₃(s) reacts with 20.0 cm³ of 2.00 mol$$dm^–3 HCl(aq)?

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)

Molar volume of gas = 22.7 dm³$$mol^–1; M_r(CaCO₃) = 100.00

A.     $\frac{1}{2}\times \frac{20.0\times 2.0}{1000}\times 22.7$

B.     $\frac{20.0\times 2.0}{1000}\times 22.7$

C.     $\frac{1.0}{100.00}\times 22.7$

D.     $\frac{1.0}{100.00}\times 2\times 22.7$

Which factors affect the molar volume of an ideal gas?

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

The sample of K₂Cr₂O₇(s) in (i) was dissolved in distilled water to form 0.100 dm³ solution. Calculate its molar concentration.

10.0 cm³ of the waste sample required 13.24 cm³ of the K₂Cr₂O₇ solution. Calculate the molar concentration of Sn²⁺(aq) in the waste sample.

Calculate the amount, in mol, of NaOH(aq) used.

Calculate the molar mass of the acid.

Explain why this experiment might give a low result for the molar mass of butane.

Suggest one improvement to the investigation.

Calculate the amounts, in mol, of each reactant.

Calculate, in g, the theoretical yield of aspirin.

What is the pressure, in Pa, inside a 1.0 m³ cylinder containing 10 kg of H₂ (g) at 25 ºC?

R = 8.31 J K^–1 mol^–1; pV = nRT

A. $\frac{1\times {10}^4\times 8.31\times 25}{1.0\times {10}^3}$

B. $\frac{5\times {10}^2\times 8.31\times 298}{1.0}$

C. $\frac{1\times 8.31\times 25}{1.0\times {10}^3}$

D. $\frac{5\times {10}^3\times 8.31\times 298}{1.0}$

Calculate the concentration of ethanoic acid, CH₃COOH, in mol dm^–3.

0.150 g sample of menthol, when vaporized, had a volume of 0.0337 dm³ at 150 °C and 100.2 kPa. Calculate its molar mass showing your working.

0.150 g sample of menthol, when vaporized, had a volume of 0.0337 dm³ at 150 °C and 100.2 kPa. Calculate its molar mass showing your working.

Urea can be made by reacting potassium cyanate, KNCO, with ammonium chloride, NH₄Cl.

KNCO(aq) + NH₄Cl(aq) → (H₂N)₂CO(aq) + KCl(aq)

Determine the maximum mass of urea that could be formed from 50.0 cm³ of 0.100 mol dm⁻³ potassium cyanate solution.

Calculate the maximum volume of CO₂, in cm³, produced at STP by the combustion of 0.600 g of urea, using sections 2 and 6 of the data booklet.

What is the percentage yield when 7 g of ethene produces 6 g of ethanol?

M_r(ethene) = 28 and M_r(ethanol) = 46

C₂H₄(g) + H₂O(g) → C₂H₅OH(g)

A.     $\frac{6\times 7\times 100}{28\times 46}$

B.     $\frac{6\times 46\times 100}{7\times 28}$

C.     $\frac{6\times 28}{7\times 46\times 100}$

D.     $\frac{6\times 28\times 100}{7\times 46}$

Urea can be made by reacting potassium cyanate, KNCO, with ammonium chloride, NH₄Cl.

                                      KNCO(aq) + NH₄Cl(aq) → (H₂N)₂CO(aq) + KCl(aq)

Determine the maximum mass of urea that could be formed from 50.0 cm³ of 0.100 mol dm⁻³ potassium cyanate solution.

What is the volume, in cm³, of the final solution if 100 cm³ of a solution containing 1.42 g of sodium sulfate, Na₂SO₄, is diluted to the concentration of 0.020 mol dm^–3?

M_r(Na₂SO₄) = 142

A.     50

B.     400

C.     500

D.     600

What is the percentage yield when 2.0 g of ethene, C₂H₄, is formed from 5.0 g of ethanol, C₂H₅OH?
M_r(ethene) = 28; M_r(ethanol) = 46

A.     $\frac{2.0}{28}\times \frac{5.0}{46}\times 100$

B.     $\frac{\frac{2.0}{28}}{\frac{5.0}{46}}\times 100$

C.     $\frac{28}{2.0}\times \frac{5.0}{46}\times 100$

D.     $\frac{\frac{28}{2.0}}{\frac{5.0}{46}}\times 100$

Calculate the amount, in mol, of H₂SO₄.

The excess sulfuric acid required 20.80 cm³ of 0.1133 mol dm⁻³ NaOH for neutralization.

Calculate the amount of excess acid present.

Calculate the amount of H₂SO₄ that reacted with Mg(OH)₂.

Calculate the percentage by mass of magnesium hydroxide in the 1.24 g antacid tablet to three significant figures.

An antacid tablet containing 0.50 g of NaHCO₃ (M_r = 84) is dissolved in water to give a volume of 250 cm³. What is the concentration, in mol dm⁻³, of HCO₃⁻ in this solution?

A.   $\frac{0.250\times 84}{0.50}$

B.   $\frac{0.50}{84\times 0.250}$

C.   $\frac{250\times 84}{0.50}$

D.   $\frac{0.50}{84\times 250}$

Determine the limiting reactant showing your working.

The mass of copper obtained experimentally was 0.872 g. Calculate the percentage yield of copper.

Determine the limiting reactant showing your working.

The mass of copper obtained experimentally was 0.872 g. Calculate the percentage yield of copper.

Outline how a solution of 0.0100 mol dm⁻³ is obtained from a standard 1.000 mol dm⁻³ copper(II) sulfate solution, including two essential pieces of glassware you would need.

Copper(II) ions are reduced to copper(I) iodide by the addition of potassium iodide solution, releasing iodine that can be titrated with sodium thiosulfate solution, Na₂S₂O₃ (aq). Copper(I) iodide is a white solid.

4I⁻ (aq) + 2Cu²⁺ (aq) → 2CuI (s) + I₂ (aq)

I₂ (aq) + 2S₂O₃²⁻ (aq) → 2I⁻ (aq) + S₄O₆²⁻ (aq)

Deduce the overall equation for the two reactions by combining the two equations.

Suggest why the end point of the titration is difficult to determine, even with the addition of starch to turn the remaining free iodine black.

Outline how a solution of 0.0100 mol dm⁻³ is obtained from a standard 1.000 mol dm⁻³ copper(II) sulfate solution, including two essential pieces of glassware you would need.

Titration is another method for analysing the solution obtained from adding brass to nitric acid.

Copper(II) ions are reduced to copper(I) iodide by the addition of potassium iodide solution, releasing iodine that can be titrated with sodium thiosulfate solution, Na₂S₂O₃ (aq). Copper(I) iodide is a white solid.

4I⁻ (aq) + 2Cu²⁺ (aq) → 2CuI (s) + I₂ (aq)

I₂ (aq) + 2S₂O₃²⁻ (aq) → 2I⁻ (aq) + S₄O₆²⁻ (aq)

Suggest why the end point of the titration is difficult to determine, even with the addition of starch to turn the remaining free iodine black.

Sodium peroxide, Na₂O₂, is formed by the reaction of sodium oxide with oxygen.

2Na₂O (s) + O₂ (g) → 2Na₂O₂ (s)

Calculate the percentage yield of sodium peroxide if 5.00g of sodium oxide produces 5.50g of sodium peroxide.

Outline why a real gas differs from ideal behaviour at low temperature and high pressure.

Explain why, as the reaction proceeds, the pressure increases by the amount shown.

The experiment is repeated using the same amount of dinitrogen monoxide in the same apparatus, but at a lower temperature.

Sketch, on the axes in question 2, the graph that you would expect.

100.0cm³ of soda water contains 3.0 × 10⁻²g NaHCO₃.

Calculate the concentration of NaHCO₃ in mol dm⁻³.

A mean daily lead intake of greater than 5.0 × 10⁻⁶ g per kg of body weight results in increased lead levels in the body.

Calculate the volume, in dm³, of tap water from experiment 8 which would exceed this daily lead intake for an 80.0 kg man.

What volume of carbon dioxide, CO₂ (g), can be obtained by reacting 1 dm³ of methane, CH₄ (g), with 1 dm³ of oxygen, O₂ (g)?

CH₄ (g) + 2O₂ (g) → CO₂ (g) + 2H₂O (l)

A. 0.5 dm³

B. 1 dm³

C. 2 dm³

D. 6 dm³

Sodium peroxide, Na₂O₂, is formed by the reaction of sodium oxide with oxygen.

2Na₂O (s) + O₂ (g) → 2Na₂O₂ (s)

Calculate the percentage yield of sodium peroxide if 5.00 g of sodium oxide produces 5.50 g of sodium peroxide.

Explain why, as the reaction proceeds, the pressure increases by the amount shown.

The experiment is repeated using the same amount of dinitrogen monoxide in the same apparatus, but at a lower temperature.

Sketch, on the axes in question 2, the graph that you would expect.

100.0 cm³ of soda water contains 3.0 × 10⁻² g NaHCO₃.

Calculate the concentration of NaHCO₃ in mol dm⁻³.

A mean daily lead intake of greater than 5.0 × 10⁻⁶ g per kg of body weight results in increased lead levels in the body.

Calculate the volume, in dm³, of tap water from experiment 8 which would exceed this daily lead intake for an 80.0 kg man.

Which graph would not show a linear relationship for a fixed mass of an ideal gas with all other variables constant?

A. P against V

B. P against $\frac{1}{\text{V}}$

C. P against T

D. V against T

What is the volume of gas when the pressure on 100 cm³ of gas is changed from 400 kPa to 200 kPa at constant temperature?

A. 50.0 cm³

B. 100 cm³

C. 200 cm³

D. 800 cm³

What is the concentration, in mol dm⁻³, of 20.0 g of NaOH (M_r = 40.0) in 500.0 cm³?

A. 0.250

B. 0.500

C. 1.00

D. 4.00

The day 5 sample contained 5.03 × 10⁻⁵ moles of oxygen.

Determine the 5-day biochemical oxygen demand of the pond, in mg dm⁻³ (“parts per million”, ppm).

Solid copper(II) chloride absorbs moisture from the atmosphere to form a hydrate of formula CuCl₂•$x$H₂O.

A student heated a sample of hydrated copper(II) chloride, in order to determine the value of $x$. The following results were obtained:

Mass of crucible = 16.221 g
Initial mass of crucible and hydrated copper(II) chloride = 18.360 g
Final mass of crucible and anhydrous copper(II) chloride = 17.917 g

Determine the value of $x$.

Calculate the pressure, in kPa, of this gas in a 10.0 dm³ air bag at 127°C, assuming no gas escapes.

1.40 × 10⁻³ g of NaOH (s) are dissolved in 250.0 cm³ of 1.00 × 10⁻¹¹ mol dm⁻³ Pb(OH)₂ (aq) solution.

Determine the change in lead ion concentration in the solution, using section 32 of the data booklet.

Calculate the pH of a buffer solution which contains 0.20 mol dm⁻³ ethanoic acid and 0.50 mol dm⁻³ sodium ethanoate. Use section 1 of the data booklet.

pK_a (ethanoic acid) = 4.76

0.10 mol of hydrochloric acid is mixed with 0.10 mol of calcium carbonate.

2HCl (aq) + CaCO₃ (s) → CaCl₂ (aq) + H₂O (l) + CO₂ (g)

Which is correct?

Solid copper(II) chloride absorbs moisture from the atmosphere to form a hydrate of formula CuCl₂•$x$H₂O.

A student heated a sample of hydrated copper(II) chloride, in order to determine the value of $x$. The following results were obtained:

Mass of crucible = 16.221 g
Initial mass of crucible and hydrated copper(II) chloride = 18.360 g
Final mass of crucible and anhydrous copper(II) chloride = 17.917 g

Determine the value of $x$.

Which volume of ethane gas, in ${\mathrm{cm}}^3$, will produce $40 {\mathrm{cm}}^3$ of carbon dioxide gas when mixed with $140 {\mathrm{cm}}^3$ of oxygen gas, assuming the reaction goes to completion?

$2{\mathrm{C}}_2{\mathrm{H}}_6 \left(\mathrm{g}\right)+7{\mathrm{O}}_2 \left(\mathrm{g}\right)\to 4{\mathrm{CO}}_2 \left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O} \left(\mathrm{g}\right)$

A.  $10$

B.  $20$

C.  $40$

D.  $80$

Calculate the amount, in $\mathrm{mol}$, of manganese(IV) oxide added.

Determine the limiting reactant, showing your calculations.

Determine the excess amount, in $\mathrm{mol}$, of the other reactant.

Calculate the volume of chlorine, in ${\mathrm{dm}}^3$, produced if the reaction is conducted at standard temperature and pressure (STP). Use section 2 of the data booklet.

Calculate the amount, in $\mathrm{mol}$, of manganese(IV) oxide added.

Determine the limiting reactant, showing your calculations.

Determine the excess amount, in $\mathrm{mol}$, of the other reactant.

Calculate the volume of chlorine, in ${\mathrm{dm}}^3$, produced if the reaction is conducted at standard temperature and pressure (STP). Use section 2 of the data booklet.

Suggest a wavenumber absorbed by methane gas.

Show that the mass of the ${}_{238}\mathrm{U}$ isotope in the rock is $0.639 \mathrm{kg}$.

Suggest a wavenumber absorbed by methane gas.

Show that the mass of the ²³⁸U isotope in the rock is $0.639 \mathrm{kg}$.

Calculate the mole fraction of ethanal in the mixture.

The vapour pressure of pure ethanal at $20°\mathrm{C}$ is $101 \mathrm{kPa}$.

Calculate the vapour pressure of ethanal above the liquid mixture at $20°\mathrm{C}$.

What volume of oxygen, in dm³ at STP, is needed when 5.8 g of butane undergoes complete combustion?

$2{\mathrm{C}}_4{\mathrm{H}}_{10} \left(\mathrm{g}\right)+13{\mathrm{O}}_2 \left(\mathrm{g}\right)\to 8{\mathrm{CO}}_2 \left(\mathrm{g}\right)+10{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)$

A.  $2\times \frac{5.8}{12.01\times 4+1.01\times 10}\times 13\times 22.7$

B.  $\frac{5.8}{12.01\times 4+1.01\times 10}\times \frac{13}{2}\times 22.7$

C.  $\frac{5.8}{12.01\times 4+1.01\times 10}\times \frac{2}{13}\times 22.7$

D.  $\frac{5.8}{12.01\times 4+1.01\times 10}\times \frac{13}{2}\times \frac{22.7}{1000}$

0.20 mol of magnesium is mixed with 0.10 mol of hydrochloric acid.

$\text{Mg\hspace{0.05em}(s)}+\text{2HCl} \text{(aq)}\to {\text{MgCl}}_{\text{2}} \text{(aq)}+{\text{H}}_{\text{2}} \text{(g)}$

Which is correct?

A gaseous sample of nitrogen, contaminated only with hydrogen sulfide, was reacted with excess sodium hydroxide solution at constant temperature. The volume of the gas changed from 550 cm³ to 525 cm³.

Determine the mole percentage of hydrogen sulfide in the sample, stating one assumption you made.

8.00 g of methane is completely converted to methanol. Calculate, to three significant figures, the final volume of hydrogen at STP, in dm³. Use sections 2 and 6 of the data booklet.

8.00 g of methane is completely converted to methanol. Calculate, to three significant figures, the final volume of hydrogen at STP, in dm³. Use sections 2 and 6 of the data booklet.

Calcium carbonate is heated to produce calcium oxide, CaO.

CaCO₃(s) → CaO (s) + CO₂(g)

Calculate the volume of carbon dioxide produced at STP when 555 g of calcium carbonate decomposes. Use sections 2 and 6 of the data booklet.

Determine the volume, in dm³, of 0.015 mol dm⁻³ calcium hydroxide solution needed to neutralize 35.0 cm³ of 0.025 mol dm⁻³ HCl (aq).

Determine the mass, in g, of CaCO₃(s) produced by reacting 2.41 dm³ of 2.33 × 10⁻² mol dm⁻³ of Ca(OH)₂ (aq) with 0.750 dm³ of CO₂ (g) at STP.

2.85 g of CaCO₃ was collected in the experiment in e(i). Calculate the percentage yield of CaCO₃.

(If you did not obtain an answer to e(i), use 4.00 g, but this is not the correct value.)

Calcium carbonate is heated to produce calcium oxide, CaO.

CaCO₃(s) → CaO (s) + CO₂(g)

Calculate the volume of carbon dioxide produced at STP when 555 g of calcium carbonate decomposes. Use sections 2 and 6 of the data booklet.

Determine the volume, in dm³, of 0.015 mol dm⁻³ calcium hydroxide solution needed to neutralize 35.0 cm³ of 0.025 mol dm⁻³ HCl (aq).

Determine the mass, in g, of CaCO₃(s) produced by reacting 2.41 dm³ of 2.33 × 10⁻² mol dm⁻³ of Ca(OH)₂ (aq) with 0.750 dm³ of CO₂ (g) at STP.

2.85 g of CaCO₃ was collected in the experiment in d(i). Calculate the percentage yield of CaCO₃.

(If you did not obtain an answer to d(i), use 4.00 g, but this is not the correct value.)

Calculate the concentration of H₃PO₄ if 25.00 cm³ is completely neutralised by the addition of 28.40 cm³ of 0.5000 mol dm⁻³ NaOH.

Calculate the amount, in moles of Na₂S₂O₃ used in the titration.

Calculate the concentration of dissolved oxygen, in mol dm⁻³, in the sample.

Calculate the concentration of H₃PO₄ if 25.00 cm³ is completely neutralised by the addition of 28.40 cm³ of 0.5000 mol dm⁻³ NaOH.

Calculate the amount, in moles of Na₂S₂O₃ used in the titration.

Calculate the concentration of dissolved oxygen, in mol dm⁻³, in the sample.

Which sample contains the fewest moles of HCl?

N_A = 6.02 × 10²³mol^–1.

Molar volume of an ideal gas at STP = 22.7 dm³mol^–1.

A.  10.0 cm³ of 0.1 mol dm^–3 HCl (aq)

B.  6.02 × 10²⁴ molecules of HCl (g)

C.  0.365 g of HCl (g)

D.  2.27 dm³ of HCl (g) at STP

Assume the reaction in (a)(i) is the only one occurring and it goes to completion, but some product has been lost from the crucible. Deduce the percentage yield of magnesium oxide in the crucible.

Evaluate whether this, rather than the loss of product, could explain the yield found in (b)(iii).

Determine the concentration, in mol dm^–3, of the solution formed when 900.0 dm³ of NH₃(g) at 300.0 K and 100.0 kPa, is dissolved in water to form 2.00 dm³ of solution. Use sections 1 and 2 of the data booklet.

Assume the reaction in (a)(i) is the only one occurring and it goes to completion, but some product has been lost from the crucible. Deduce the percentage yield of magnesium oxide in the crucible.

Evaluate whether this, rather than the loss of product, could explain the yield found in (b)(iii).

Determine the concentration, in mol dm^–3, of the solution formed when 900.0 dm³ of NH₃(g) at 300.0 K and 100.0 kPa, is dissolved in water to form 2.00 dm³ of solution. Use sections 1 and 2 of the data booklet.

Calculate the molar concentration of the resulting solution of lithium hydroxide.

Calculate the volume of hydrogen gas produced, in cm³, if the temperature was 22.5 °C and the pressure was 103 kPa. Use sections 1 and 2 of the data booklet.