DP Chemistry Questionbank

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

Calculate the molar mass of the acid.

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

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.  $2.4\times {10}^{23}$

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.  $26$

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.

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).

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

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

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

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

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.

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.

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.

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 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.

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

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

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

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.

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

Determine the limiting reactant showing your working.

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.

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.

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

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