The pH scale & neutralisation

This question is about acids.

A student investigated the volume of an alkali needed to react completely with

Figure 10 shows the apparatus.

This is the method used.

1. Add 25 cm³ of the acid to a beaker.

2. Add a piece of universal indicator paper to the acid.

3. Add the alkali drop by drop to the acid until the universal indicator paper changes colour to green.

4. Record the number of drops of alkali added.

The method does not give an accurate volume of alkali needed to react completely with the acid.

Suggest two improvements to the method.

What is the pH of the solution when the universal indicator paper turns green?

Tick () one box.

What name is given to the reaction between an acid and an alkali?

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Which ion do all acids contain?

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Name the acid that reacts with sodium hydroxide to produce sodium nitrate.

Figure 11 shows a reaction profile for the reaction between an acid and an alkali.

What do labels A and B represent on Figure 11 ?

Choose the answers from the box.

Acids also react with insoluble solid substances to produce salt solutions.

When making a salt solution, excess solid is added to the acid.

Draw the apparatus used to separate the excess solid from the salt solution by filtration.

The apparatus should collect:

• the excess solid

• the salt solution.

Solid X reacts with hydrochloric acid to produce zinc chloride and hydrogen gas.

Name solid X.

Nitric acid (HNO₃) is a strong acid.

What is meant by a ‘strong acid’?

Nitric acid is used as a dilute aqueous solution.

What is meant by ‘dilute aqueous solution’?

10 cm³ of a nitric acid solution has a pH of 1

Water is added to the nitric acid solution to change the pH of the nitric acid solution to pH 3

How does the hydrogen ion concentration change?

Tick () one box.

Write the ionic equation for the reaction between an acid and an alkali.

The equation shows the reaction between magnesium carbonate and nitric acid.

What is the ratio of the number of moles of magnesium carbonate to the number of moles of nitric acid in the reaction?

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A student mixed some magnesium carbonate with excess nitric acid.

The student then added two drops of universal indicator to the solution.

What colour was the solution after the addition of universal indicator?

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A student investigated the temperature change when different masses of

magnesium carbonate were reacted with excess nitric acid.

Figure 6 shows the apparatus.

This is the method used.

1. Pour 50 cm³ of nitric acid into a polystyrene cup.

2. Measure the temperature of the solution.

3. Add 0.50 g of magnesium carbonate.

4. Stir the mixture.

5. Measure the temperature.

6. Repeat steps 1 to 5 with different masses of magnesium carbonate.

Give two improvements to the method to produce more accurate results.

Do not refer to improvements to the apparatus in your answer.

This question is about carbon dioxide.

Carbon dioxide is soluble in water and forms an acidic solution.

Which ion makes the solution acidic?

Name an indicator that could be used to test if the solution is acidic. Give the result of the test.

Figure 14 shows the mass of carbon dioxide that will dissolve in 1 dm³ of water

at different temperatures.

How does the solubility of carbon dioxide change as the temperature of the

Tick (✓) one box.

Carbon dioxide dissolves in water to form an acidic solution. How does the pH of the solution change as the temperature of the water increases?

Tick (✓) one box.

Calcium carbonate reacts with hydrochloric acid to produce carbon dioxide. The equation for the reaction is:

What is the state symbol (x) in the equation? Tick (✓) one box.

Figure 15 shows equipment a student used for an investigation.

The student investigated the volume of carbon dioxide produced when different

masses of calcium carbonate react with hydrochloric acid. Describe a method the student could use.

This question is about carbon dioxide.

Carbon dioxide is soluble in water and forms an acidic solution.

Which ion makes the solution acidic?

Name an indicator that could be used to test if the solution is acidic. Give the result of the test.

Figure 1 shows the mass of carbon dioxide that will dissolve in 1 dm³ of water

at different temperatures.

How does the solubility of carbon dioxide change as the temperature of the

Tick (✓) one box.

Carbon dioxide dissolves in water to form an acidic solution. How does the pH of the solution change as the temperature of the water increases?

Tick (✓) one box.

Calcium carbonate reacts with hydrochloric acid to produce carbon dioxide. The equation for the reaction is:

What is the state symbol (x) in the equation? Tick (✓) one box.

Figure 2 shows equipment a student used for an investigation.

The student investigated the volume of carbon dioxide produced when different

masses of calcium carbonate react with hydrochloric acid. Describe a method the student could use.

This question is about hydrogen chloride and sodium hydroxide.

A chlorine atom has 7 electrons in the outer shell. A hydrogen atom has 1 electron in the outer shell. Figure 4 represents part of a dot and cross diagram for a molecule of hydrogen chloride.

Complete the dot and cross diagram. Use dots (ο) and crosses (x) to represent electrons. You should show only the electrons in the outer shells.

Hydrogen chloride dissolves in water to produce hydrochloric acid. Hydrochloric acid reacts with sodium hydroxide solution. Complete the word equation for the reaction between hydrochloric acid and sodium hydroxide.

hydrochloric acid + sodium hydroxide → + water

Solutions of hydrochloric acid and sodium hydroxide are reacted and the temperature change is recorded.

In the reaction, 3.65 g of hydrogen chloride reacts with 4.00 g of sodium hydroxide. 1.80 g of water is produced. Calculate the mass of the other product.

Figure 5 shows part of the thermometer used to measure the temperature.

What is the temperature reading on the thermometer?

In the reaction, the temperature increases. What type of reaction is happening when the temperature increases?

Sodium hydroxide is an alkali. Which two ions are in sodium hydroxide solution? Tick (✓) two boxes.

This question is about salts. Green copper carbonate and sulfuric acid can be used to produce blue copper sulfate crystals.

Excess copper carbonate is added to sulfuric acid. Give three observations you would make.

How can the excess copper carbonate be removed?

The pH of the solution changes during the reaction. What is the pH of the solution at the end of the reaction?

Copper carbonate and sulfuric acid react to produce copper sulfate. What type of reaction is this?

Ammonium nitrate is a salt. Figure 13 shows the maximum mass of ammonium nitrate that can dissolve in 100 cm³ of water at different temperatures.

A student adds ammonium nitrate to water at 80 °C until no more dissolves. The student cools 100 cm³ of this solution of ammonium nitrate from 80 °C to 20 °C to produce crystals of ammonium nitrate.

Determine the mass of ammonium nitrate that crystallises on cooling 100 cm³ of this solution from 80 °C to 20 °C

This question is about salts. Green copper carbonate and sulfuric acid can be used to produce blue copper sulfate crystals.

Excess copper carbonate is added to sulfuric acid. Give three observations you would make.

How can the excess copper carbonate be removed?

The pH of the solution changes during the reaction. What is the pH of the solution at the end of the reaction?

Copper carbonate and sulfuric acid react to produce copper sulfate. What type of reaction is this?

Ammonium nitrate is a salt. Figure 1 shows the maximum mass of ammonium nitrate that can dissolve in 100 cm³ of water at different temperatures.

A student adds ammonium nitrate to water at 80 °C until no more dissolves. The student cools 100 cm³ of this solution of ammonium nitrate from 80 °C to 20 °C to produce crystals of ammonium nitrate.

Determine the mass of ammonium nitrate that crystallises on cooling 100 cm³ of this solution from 80 °C to 20 °C

Acids react to produce salts. Universal indicator is added to water and then nitric acid is added to the mixture.

Give the colour change when nitric acid is added to the mixture of universal indicator and water. Tick (✓) one box.

What happens to the pH of water when nitric acid is added? Tick (✓) one box.

What is the state symbol for nitric acid?

Zinc carbonate reacts with nitric acid.

The word equation for the reaction is: zinc carbonate + nitric acid → zinc nitrate + water + carbon dioxide white solid colourless solution

Give two observations that would be made when zinc carbonate is added to nitric acid until the zinc carbonate is in excess.

The formula of the zinc ion is Zn²⁺ The formula of the nitrate ion is NO₃^– What is the formula for zinc nitrate? Tick (✓) one box.

Acids react with insoluble metal oxides to produce salts. Plan a method to produce a pure, dry sample of the soluble salt copper chloride from an acid and a metal oxide.

Acids react to produce salts. Universal indicator is added to water and then nitric acid is added to the mixture.

Give the colour change when nitric acid is added to the mixture of universal indicator and water. Tick (✓) one box.

What happens to the pH of water when nitric acid is added? Tick (✓) one box.

What is the state symbol for nitric acid?

Zinc carbonate reacts with nitric acid.

The word equation for the reaction is: zinc carbonate + nitric acid → zinc nitrate + water + carbon dioxide white solid colourless solution

Give two observations that would be made when zinc carbonate is added to nitric acid until the zinc carbonate is in excess.

The formula of the zinc ion is Zn²⁺ The formula of the nitrate ion is NO₃^– What is the formula for zinc nitrate? Tick (✓) one box.

Acids react with insoluble metal oxides to produce salts. Plan a method to produce a pure, dry sample of the soluble salt copper chloride from an acid and a metal oxide.

This question is about acids and bases.

What is the pH of sulfuric acid? Tick (✓) one box.

An acid reacts with zinc to produce zinc chloride and hydrogen. Which acid reacts with zinc to produce zinc chloride? Tick (✓) one box.

What type of substance is zinc chloride? Tick (✓) one box.

An alkali is a base in solution. Which compound is an alkali? Tick (✓) one box.

The formula of the copper ion is Cu²⁺ The formula of the oxide ion is O^2– What is the formula of copper oxide? Tick (✓) one box.

A student reacts an acid with copper oxide.

The reaction between the acid and copper oxide is very slow at room temperature. How could the student speed up the reaction?

Complete the sentence to show how the student makes sure that all the acid reacts. Choose the answer from the box.

The student adds copper oxide to the acid until the copper oxide is.

The student filters the unreacted copper oxide from the solution. Which apparatus does the student use? Tick (✓) one box.

What process is used to produce crystals of a salt from a salt solution?

This question is about acids, alkalis and bases. A student reacted zinc oxide powder with hydrochloric acid to produce zinc chloride solution.

Complete the equation for the reaction by writing the state symbols.

Give one way that the student could speed up the reaction between zinc oxide powder and hydrochloric acid.

Hydrochloric acid was the limiting reactant.

How could the student know when all the hydrochloric acid has reacted?

How could the student obtain zinc chloride solution from the reaction mixture when all the hydrochloric acid has reacted?

Describe how zinc chloride crystals are produced from zinc chloride solution.

Sulfuric acid and sodium hydroxide react to produce sodium sulfate.

Sulfuric acid is gradually added to sodium hydroxide solution. The pH of the mixture changes as the sulfuric acid is added until in excess. Suggest the pH at:

• the start before sulfuric acid is added

• the end when sulfuric acid is in excess.

Complete the symbol equation for the preparation of sodium sulfate. You should balance the equation.

A solution of hydrochloric acid had a hydrogen ion concentration of 1.0 mol/dm³ Water was added to the hydrochloric acid until the pH increased by 1 What was the hydrogen ion concentration of the hydrochloric acid after water had been added? Tick (✓) one box.

This question is about salts. Ammonium nitrate solution is produced when ammonia gas reacts with nitric acid.

Give the state symbol for ammonium nitrate solution.

What is the formula of nitric acid? Tick (✓) one box.

Ammonia gas dissolves in water to produce ammonia solution. Ammonia solution contains hydroxide ions, OH^– A student adds universal indicator to solutions of nitric acid and ammonia. What colour is observed in each solution?

Colour in nitric acid Colour in ammonia solution

The student gradually added nitric acid to ammonia solution. Which row, A, B, C or D, shows the change in pH as the nitric acid is

Calculate the percentage by mass of oxygen in ammonium nitrate (NH₄NO₃). Relative atomic masses (A_r): H = 1 N = 14 O = 16 Relative formula mass (M_r): NH₄NO₃ = 80

Describe a method to investigate how the temperature changes when different masses of ammonium nitrate are dissolved in water. You do not need to write about safety precautions.

This question is about salts. Ammonium nitrate solution is produced when ammonia gas reacts with nitric acid.

Give the state symbol for ammonium nitrate solution.

What is the formula of nitric acid? Tick (✓) one box.

Ammonia gas dissolves in water to produce ammonia solution. Ammonia solution contains hydroxide ions, OH^– A student adds universal indicator to solutions of nitric acid and ammonia. What colour is observed in each solution?

Colour in nitric acid Colour in ammonia solution

The student gradually added nitric acid to ammonia solution. Which row, A, B, C or D, shows the change in pH as the nitric acid is

Calculate the percentage by mass of oxygen in ammonium nitrate (NH₄NO₃). Relative atomic masses (A_r): H = 1 N = 14 O = 16 Relative formula mass (M_r): NH₄NO₃ = 80

Describe a method to investigate how the temperature changes when different masses of ammonium nitrate are dissolved in water. You do not need to write about safety precautions.

This question is about acids and bases.

Which ion is found in all acids? Tick one box.

Zinc nitrate can be produced by reacting an acid and a metal oxide. Name the acid and the metal oxide used to produce zinc nitrate.

In an equation, zinc nitrate is written as Zn(NO₃)₂(aq). What does (aq) mean? Tick one box.

The pH of a solution is 8 Some hydrochloric acid is added to the solution. Suggest the pH of the solution after mixing.

Table 2 shows the solubility of three solids in water at room temperature.

A teacher labelled these three solids A, B and C. She gave a student the information shown in Table 3

Describe a method that could be used to identify each of the three solids A, B and C. You must use an indicator in the method. Use information in Table 2 and Table 3

A scientist does two tests on four white solids. The solids are labelled A, B, C and D Test 1 Adds the sample of the solid to distilled water and stirs. Test 2 Measures the pH of the solution after Test 1 Table 2 shows the results.

These four solids are:

• magnesium oxide

• phosphorus oxide

• silicon dioxide

• sodium oxide.

Table 3 shows the solubility of these four solids in water.

Identify the solids A, B, C and D. Explain your answers.

10 cm³ of solution B is added to a beaker. Distilled water is added to the beaker until the final volume in the beaker is 1000 cm³ The pH of the solution is measured before and after distilled water is added. Table 4 shows the results.

Calculate the value of X.