IB myp 4-5 Chemistry – Practice Questions- All Topics
Topic :Types of chemical reaction-Acids and bases
Topic :Types of chemical reaction-Weightage : 21 %
All Questions for Topic :acids and bases,neutral solutions,acid/base reactions,$\mathrm{pH}$ and indicators,formation of salts,uses of salts,redox reactions,reactivity series,extraction of metals and corrosion,electrochemical cells
Question (9 marks)
Phosphoric acid (H3PO4) is added to cola to provide a sour taste that balances the sweetness of sucrose.
Question a (2 marks)
Calculate the molar mass of phosphoric acid (H3PO4) with units.
▶️Answer/Explanation
Answer:
98.00 g mol-1
Explanation:
Calculation:
3(H) = 3 × 1.01 = 3.03
1(P) = 30.97
4(O) = 4 × 16.00 = 64.00
Total = 3.03 + 30.97 + 64.00 = 98.00 g mol-1
Question b (2 marks)
Calculate the moles of sucrose (C12H22O11) in 39g (molar mass = 342.3 g mol-1) to 3 significant figures.
▶️Answer/Explanation
Answer:
0.114 mol
Explanation:
n = m/M = 39 g / 342.3 g mol-1 = 0.1139 mol ≈ 0.114 mol
Question c (3 marks)
Determine the molecular formula of xylitol (artificial sweetener) from its structural formula.
▶️Answer/Explanation
Answer:
C5H12O5
Explanation:
From the structural diagram (not shown here):
• 5 carbon atoms
• 12 hydrogen atoms
• 5 hydroxyl (OH) groups → 5 oxygen atoms
Question d (2 marks)
Identify the functional groups in aspartame (artificial sweetener):
▶️Answer/Explanation
Answer:
• Carboxylic acid (-COOH)
• Ester (-COOCH3)
Explanation:
From the structural diagram:
1. The -COOH group is characteristic of carboxylic acids
2. The -COOCH3 group shows an ester linkage
Question:
Consider the reactions of the following Group 3 oxides with water: sodium oxide, aluminium oxide, and sulfur dioxide. Describe whether each is acting as an acid or base. What does this suggest about the change in acid–base properties across a period?
▶️Answer/Explanation
Ans: Sodium oxide is acting as a basic oxide; aluminium oxide is amphoteric and can act as both a basic and acidic oxide; sulfur dioxide is acting as an acidic oxide; the general trend across period 3 of the periodic table is a change from basic to acidic oxides.