GCSE AQA Chemistry Rate of Reaction: 4 (a) (i) Give the name of a car

Question

4 (a) (i) Give the name of a carbonate in scale.

Calcium carbonate is a common carbonate found in scale.

4 (a) (ii) When acids react with scale a gas is produced.
What is the name of the gas?

The gas produced is carbon dioxide.

4 (b) Ethanoic acid is used to remove scale.
Complete the displayed structure of ethanoic acid (CH₃COOH).

The displayed structure of ethanoic acid is:

```
    H   O
     \  ||
      C--C
     /    \
    H      OH
```

4 (c) (i) The student found that hydrochloric acid reacts faster than ethanoic acid with scale.
Explain why hydrochloric acid reacts faster than ethanoic acid.

Hydrochloric acid reacts faster because it is a stronger acid, which means it dissociates more completely in solution compared to ethanoic acid. This results in a higher concentration of hydrogen ions (H⁺) in solution, enhancing the reaction rate with scale.

4 (c) (ii) Hydrochloric acid should not be used to dissolve scale in kettles.
Suggest why.

Hydrochloric acid is corrosive and can damage the kettle, especially if it is made of a sensitive material.

4 (d) A student does a titration to find the concentration of a solution of hydrochloric acid.
The student titrates 25.00 cm³ of hydrochloric acid with sodium hydroxide solution of concentration 0.200 moles per dm³. The equation for the reaction is:

HCl + NaOH ⇌ NaCl + H₂O

The student added 28.60 cm³ of sodium hydroxide solution to neutralise the hydrochloric acid.
Calculate the concentration of the hydrochloric acid.

To calculate the concentration of hydrochloric acid, we can use the following steps:
1. Calculate the number of moles of NaOH used:
   
   Number of moles = concentration × volume = 0.200 mol/dm³ × (28.60 cm³ × 1 dm³ / 1000 cm³) = 0.00572 mol.
   
2. The reaction is a 1:1 ratio, so the moles of HCl will also be 0.00572 mol.
   
3. Calculate the concentration of HCl:
   
   Concentration = moles/volume = 0.00572 mol / (25.00 cm³ × 1 dm³ / 1000 cm³) = 0.2288 mol/dm³.

4 (a) (i) Give the name of a carbonate in scale - AQA - GCSE Chemistry - Question 4 - 2014 - Paper 3

Worked Solution & Example Answer:4 (a) (i) Give the name of a carbonate in scale - AQA - GCSE Chemistry - Question 4 - 2014 - Paper 3

Give the name of a carbonate in scale.

What is the name of the gas?

Complete the displayed structure of ethanoic acid (CH₃COOH).

Explain why hydrochloric acid reacts faster than ethanoic acid.

Suggest why hydrochloric acid should not be used to dissolve scale in kettles.

Calculate the concentration of the hydrochloric acid.

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