IB DP Chemistry -Reactivity 2.1 How much? The amount of chemical change- IB Style Questions For HL Paper 1A -FA 2025

IBDP Chemistry HL Paper 1A & 1B - All Chapters

Question 

What is the theoretical yield, in \( \mathrm{g} \), of ethanamide, \( \mathrm{CH_3CONH_2} \), that can be produced from the reaction of \(4.00\,\mathrm{g}\) of ammonium carbonate, \( \mathrm{(NH_4)_2CO_3} \), with excess ethanoic acid, \( \mathrm{CH_3COOH} \)?

\( \mathrm{2CH_3COOH(l)+(NH_4)_2CO_3(s)\rightarrow2CH_3COONH_4(aq)+H_2O(l)+CO_2(g)} \)

\( \mathrm{CH_3COONH_4(aq)\rightarrow CH_3CONH_2(s)+H_2O(l)} \)

\( M_{\mathrm{r}}\mathrm{((NH_4)_2CO_3)}=96.11 \)

\( M_{\mathrm{r}}\mathrm{(CH_3CONH_2)}=59.08 \)

(A) \(1.23\)
(B) \(2.46\)
(C) \(4.92\)
(D) \(6.51\)
▶️ Answer/Explanation

Correct Answer: \( \boxed{\mathrm{B}} \)

First calculate the amount of ammonium carbonate:

\(n=\dfrac{4.00}{96.11}=0.04162\,\mathrm{mol}\)

From the equations, \(1\) mol of \( \mathrm{(NH_4)_2CO_3} \) produces \(2\) mol of \( \mathrm{CH_3COONH_4} \), and each mole of \( \mathrm{CH_3COONH_4} \) produces \(1\) mol of \( \mathrm{CH_3CONH_2} \).

Therefore:

\(n(\mathrm{CH_3CONH_2})=2\times0.04162=0.08324\,\mathrm{mol}\)

Theoretical mass of ethanamide:

\(m=0.08324\times59.08=4.92\,\mathrm{g}\)

Therefore, the correct answer is (C).

Question 

The volume of ethyne as it reacts with hydrogen is shown in the graphs.

\( \mathrm{C_2H_2(g)+2H_2(g)\rightarrow C_2H_6(g)} \)

Which graph shows how the volume of hydrogen changes with time?

▶️ Answer/Explanation

Correct Answer: \( \boxed{\mathrm{D}} \)

From the balanced equation:

\( \mathrm{C_2H_2+2H_2\rightarrow C_2H_6} \)

The stoichiometric ratio is:

\( \mathrm{C_2H_2:H_2=1:2} \)

Therefore, for every unit volume of \( \mathrm{C_2H_2} \) consumed, twice that volume of \( \mathrm{H_2} \) is consumed.

The graph for \( \mathrm{H_2} \) must therefore show a greater decrease in volume than the graph for \( \mathrm{C_2H_2} \), while both volumes decrease with time and eventually become constant when the reaction is complete.

Graph D shows this relationship, so the correct answer is (D).

Question

Four identical containers under the same conditions are filled with gases as shown below. Which container and contents will have the highest mass?
▶️ Answer/Explanation
Detailed solution

All containers have the same:

  • volume
  • temperature
  • pressure

Under identical conditions, the number of moles in each container is the same (from the ideal gas law).

Therefore, the container with the largest molar mass will have the greatest total mass.

Molar masses:

  • \( M(\text{N}_2) = 28 \)
  • \( M(\text{O}_2) = 32 \)
  • \( M(\text{C}_2\text{H}_6) = 30 \)
  • \( M(\text{Ne}) = 20 \)

Oxygen has the largest molar mass, so its container will have the greatest mass.

✅ Answer: B

More DP Chemistry HL Paper 1 Questions..
Scroll to Top