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

D

What is the molecular formula of a hydrocarbon containing 84.6% carbon by mass with a molar mass of 142.3 g mol⁻¹?

A.     C₂₀H₄₄

B.     C₁₁H₁₀

C.     C₁₀H₂₂

D.     C₅H₁₁

C

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

D

Very well answered. 88 % of the candidates balanced the equation and added up the integer coefficients correctly.

Which is correct?

A. Mixtures are either homogeneous or heterogeneous and their chemical properties are an average of the individual component properties.

B. Mixtures are never heterogeneous and their chemical properties are an average of the individual component properties.

C. Mixtures are either homogeneous or heterogeneous and the components retain their individual chemical properties.

D. Mixtures are never homogeneous and the components retain their individual chemical properties.

C

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

B

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.  $26$

A

70% of candidates correctly found the molar mass of a substance given the mass of 0.200 mol. Good to see that very few were fooled by the same answer but incorrect significant figures.

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

B

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

A

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?

C

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

D

This question was well answered while one teacher commented that using 1 as a coefficient in a “sum the coefficients” question seemed tricky.

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

B

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

D

Which statement describes all homogeneous mixtures?

A.  Any sample has the same ratio of the components.

B.  The components are covalently bonded together.

C.  The components cannot be easily separated.

D.  The mixture needs a specific ratio of components to form.

A

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

D

8.8 g of an oxide of nitrogen contains 3.2 g of oxygen. What is the empirical formula of the compound?

A.  N₂O₅

B.  N₂O

C.  NO₂

D.  NO

B

Which is a homogeneous mixture?

A.     Oil and water

B.     Sand and water

C.     Ethanol and water

D.     Chalk and sand

C

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

C

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

B

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

D

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

A

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.  $80$

B

More than 65% of candidates were able to apply coefficient ratios in a stoichiometry question involving only gaseous reactants and products.

Which contains the most atoms of oxygen?

A.  64 g of O₂

B.  1.2 × 10²⁴ molecules of O₂

C.  64 g of C₃H₅O₃

D.  1.2 × 10²⁴ molecules of C₃H₅O₃

D

Which molecule has the same empirical formula as molecular formula?

A.  CH₃COOH

B.  C₂H₅OH

C.  C₂H₄

D.  C₄H₁₀

B

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

A

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)

B

58% of the candidates identified the equation that represented the deposition of iodine. The most commonly chosen distractor was the condensation of gaseous iodine. Sublimation was also quite commonly chosen.

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

C

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

D

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

C

Which amount, in mol, of sodium chloride is needed to make 250 cm³ of 0.10 mol dm⁻³ solution?

A.  4.0 × 10⁻⁴

B.  0.025

C.  0.40

D.  25

B

Which diagram represents a heterogeneous mixture?

A

A few G2 forms suggested that candidates could have chosen A or B. However, homogeneous and heterogeneous mixtures are usually represented in such a way while only option A shows a clear separation in the mixture. We will avoid schematic diagrams in the future for this type of questions.

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

C

What is the number of atoms of oxygen in 2.0 mol of hydrated sodium carbonate, Na₂CO₃•10H₂O? Avogadro’s constant, L or N_A: 6.02 × 10²³ mol^–1

A.     6

B.     26

C.     3.6 × 10²⁴

D.     1.6 × 10²⁵

D

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

B

One of the best answered questions on paper 1. Very few of the candidates struggled with distinguishing molecular and empirical formula.

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

C

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

A

The idea of P vs 1/V as being non-linear was the most common mistake, with just over 50 % of candidates earning this mark.

30 g of an organic compound produces 44 g CO₂ and 18 g H₂O as the only combustion products. Which of the following is the empirical formula for this compound?

M_r CO₂ = 44 M_r H₂O = 18

A.  CH₂

B.  CH₃

C.  CHO

D.  CH₂O

D

63% of the candidates determined the empirical formula of the organic compound correctly using the masses of the sample and the combustion products.

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

C

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

C

75 % of the candidates were able to calculate the molar concentration of the NaOH solution. The question had a good discrimination index.

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

C

80 % of the candidates were able to deduce the new volume of a sample of gas after the pressure was halved. The most commonly chosen distractor (A) was the value that assumed a direct proportionality between volume and pressure.

Which compound has the greatest percentage by mass of nitrogen atoms?

A.     N₂H₄

B.     NH₃

C.     N₂O₄

D.     NaNO₃

A

The two containers shown are connected by a valve. What is the total pressure after the valve is opened and the two gas samples are allowed to mix at constant temperature?

A.  1.5 × 10⁵Pa

B.  2.3 × 10⁵Pa

C.  2.5 × 10⁵Pa

D.  5.0 × 10⁵Pa

B

What is the empirical formula of a hydrocarbon with 75 % carbon and 25 % hydrogen by mass?

A. C₃H

B. CH₂

C. C₂H₆

D. CH₄

D

Well answered and straight forward.

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

C

What is the molecular formula of a compound with an empirical formula of CHO₂ and a relative molecular mass of 90?

A.  CHO₂

B.  C₂H₂O₄

C.  C₃H₆O₃

D.  C₄H₁₀O₂

B

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

D

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

C

This was one of the easier questions on the paper. 79 % of the candidates were able to deduce the amount of a product given the amount of another product and the balanced equation.

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

B

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

B

What is the concentration of chloride ions, in mol dm⁻³, in a solution formed by mixing 200 cm³ of 1 mol dm⁻³ HCl with 200 cm³ of 5 mol dm⁻³ NaCl?

A.  1

B.  2

C.  3

D.  6

C

52% of the candidates calculated the concentration of chloride ions in the titration. The distractors were chosen almost equally.

What is the resulting concentration, in mol dm⁻³, when 1.0 cm³ of 0.500 mol dm⁻³ nitric acid solution is diluted to 50.0 cm³ with water?

A.  0.002

B.  0.01

C.  0.04

D.  0.1

B

The volume of a sample of gas measured at 27 °C is 10.0 dm³. What is the temperature when the volume is reduced to 9.0 dm³ at the same pressure?

A.   −3.0 °C

B.   24.3 °C

C.   29.7 °C

D.   57.0 °C

A

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

B

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

A

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.   $\frac{0.50}{84\times 250}$

B

Which combination is correct?

B

Which electron transition emits energy of the longest wavelength?

A

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.  $2.4\times {10}^{23}$

D

Approximately 57% of candidates could correctly apply Avogadro's number in calculating number of carbon atoms in 12 g of ethanoic acid. Many candidates did not identify that there were 2 carbon atoms per molecule.

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

D

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

B

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 

C

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)

B

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?

C

Which graph shows the relationship between the volume and pressure of a fixed mass of an ideal gas?

A

Which graph represents the relationship between the amount of gas, n, and the absolute temperature, T, with all other variables in the ideal gas equation, PV = nRT, held constant?

B

56% of the candidates selected the correct graph representing the relationship between the amount of gas and its absolute temperature. The most commonly chosen distractor gave a directly proportional relationship.