Measurement, data processing & analysis (Second test)

1. What is the best way to minimise the random uncertainty when performing an acid-base titration?

A. Use a different pipette

B. Use a pH meter rather than an indicator to determine the end point

C. Repeat the titration several times

D. Keeping your eye at the same height as the meniscus when reading the burette

2. Which will give the greatest uncertainty when measuring 50.00 cm³ of a liquid?

A. Graduated 50cm³ pipette

B. Graduated 50 cm³ burette

C. 50 cm³ volumetric flask

D. 50cm³ measuring cylinder

3. A student performed an experiment three times to determine a value for the melting point of a compound. The three values she obtained were 112 ^oC, 111 ^oC and 112 ^oC. The literature value for the melting point is 122 ^oC. Which best describes her data?

A. Her measurements involve low accuracy and high precision.

B. Her measurements involve low accuracy and low precision.

C. Her measurements involve high accuracy and high precision.

D. Her measurements involve high accuracy and low precision.

4. A thermometer with an accuracy of ± 0.2 ^oC was used to measure an initial temperature of 25.4 ^oC and a final temperature of 18.4 ^oC. Which is the correct way to record the temperature drop?

A. 7 ^oC

B. 7.0 ^oC

C. 7.0 ± 0.2 ^oC

D. 7.0 ± 0.4 ^oC

5. Three sets each of five measurements of the same physical quantity were made. The accurate value of the quantity was 20.0. Which results could be described as precise?

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

6. A piece of metal with a mass of 20.000 g was placed in water in a graduated cylinder. The water level was observed to rise from 34.4 cm³ to 39.4 cm³. Which is the correct way to report the density of the metal?

A. 4 g cm^-3

B. 4.0 g cm^-3

C. 4.00 g cm^-3

D. 4.000 g cm^-3

7. A 250 cm³ volumetric flask with an uncertainty of 0.5 cm³ is used to measure 250 cm³ of 0.100 ± 0.001 mol dm^-3 hydrochloric acid solution. What is the amount in moles of hydrochloric acid present in the measured volume?

A. 0.0250 ± 0.0003

B. 0.0250 ± 0.0030

C. 0.0250 ± 0.0012

D. 0.0250 ± 0.0001

8. Three different types of apparatus were used in an experiment to find the molar mass of a compound. The relative uncertainty associated with each piece of apparatus was 1%, 1% and 3% respectively. What is the uncertainty for the determined value of the
molar mass?

A. 1%

B. 3%

C. 5%

D. 6%

9. The ideal gas equation is pV = nRT. For a fixed amount of an ideal gas at a constant temperature which statements are correct?

I. A graph of P against V will be a curve

II. A graph of P against 1/V will be a straight line

III. The pressure is inversely proportional to the volume

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

10. The graph below show how the concentration of one of the products, P, from a reaction changes as the reaction proceeds.

Which are correct statements about the rate of this reaction?

I. The rate of the reaction at time t = ∆[P]/∆T

II. The units for the rate of reaction are mol dm^-3 s^-1

III. The concentration of the product is directly proportional to time

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

11. Which region of the electromagnetic spectrum has the wavelength of ultraviolet light?

A. 10^-8 m

B. 10^-5 m

C. 10^-2 m

D. 10² m

12. Which is correct about the regions of the electromagnetic spectrum?

13. What is the index of hydrogen deficiency (IHD) of C₁₀H₂₀?

A. 0

B. 1

C. 2

D. 20

14. An organic compound containing only carbon and hydrogen has an index of hydrogen
deficiency (IHD) of one. Which statement about the compound is consistent with this
information.

A. It is an alkyne.

B. It is a cycloalkane.

C. It contains an aldehyde functional group.

D. It is a branched alkane

15. Which compound contains at least one peak in its ¹H NMR spectrum that is split into a doublet?

A. CH₃CH₂COOH

B. CH₂CH₂

C. (CH₃)₂CHCOCH₂CH₃

D. (CH₃)₃CCOOH

16. Which isomer of C₃H₆O₂ has a different number of peaks to the other three isomers in its ¹H NMR spectrum?

A. CH₃CH₂COOH

B. CH₃COOCH₃

C. HCOOCH₂CH₃

D. CH₃OCH₂CHO

17. Which three statements about the ¹H NMR spectrum of methyl propanoate, CH₃CH₂COOCH₃, are all correct.

18. Propanal, CH₃CH₂CHO, undergoes fragmentation in a mass spectrometer. Which value for m/z will not show up as a line in its mass spectrum?

A. 15

B. 29

C. 44

D. 58

19. Which is a correct statement about the use of spectroscopy to determine the structure of an organic compound?

A. X-ray crystallography provides information on the bond angles in a molecule of the compound.

B. Infrared spectroscopy can be used to help determine the number of hydrogen atoms in a molecule of the compound.

C. Mass spectrometry can be used to determine the bond lengths in a molecule of the compound.

D. ¹H NMR provides information on the chemical environment of each carbon atom in a molecule of the compound.

20. The infrared spectrum of a compound shows a very broad absorption centred at 3325 cm^-1 but no absorption at around 1700 cm^-1. Which class of compound is it most likely to belong to?

A. carboxylic acid

B. aldehyde

C. ester

D. alcohol

Answers

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