The pH scale & neutralisation

This question is about alkalis and acids.

What is the formula of the ion that all alkalis contain when in solution?

A student planned a titration experiment to determine the concentration of a sodium hydroxide solution.

This is the student’s plan.

1. Measure 25.0 cm³ of sulfuric acid of known concentration using a pipette.

2. Add the sulfuric acid to a conical flask.

3. Add 3 drops of universal indicator to the conical flask.

4. Place the conical flask on a white tile.

5. Fill a burette with sodium hydroxide solution to the 0.00 cm³ mark.

6. Add sodium hydroxide solution to the conical flask and swirl the flask.

7. Stop adding sodium hydroxide solution when there is a colour change.

8. Record the volume of sodium hydroxide solution used.

9. Repeat steps 1 to 8 until consistent results are obtained.

Suggest two improvements to the plan.

Give one reason for each improvement.

Figure 9 shows the burette after one titration.

What is the reading on the burette?

In a different titration, 25.0 cm³ of 0.216 mol/dm³ sulfuric acid needed 11.25 cm³ of sodium hydroxide solution for neutralisation.

The equation for the reaction is:

Calculate the concentration of the sodium hydroxide solution.

Table 4 gives information about solutions of two acids.

Which is a correct statement about the solutions of HC l and HCN in Table 4 ?

Tick () one box.

In Table 4, the solution of HC l has a lower pH than the solution of HCN.

Explain why.

Use the data in Table 4.

This question is about acids and their reactions.

Acids can be either weak or strong.

What is meant by ‘a weak acid’?

Explain what happens to the pH of an acid as the acid is diluted with water.

A student does a titration to find the volume of acid needed to neutralise an alkali.

The student fills a burette with the acid.

Give three more steps the student must do before adding the acid to the alkali from the burette.

You should name any equipment used.

The student titrated a solution containing 0.0045 moles of sodium hydroxide with 0.15 mol/dm³ hydrochloric acid.

The equation for the reaction is:

Calculate the volume of hydrochloric acid in cm³ needed in the titration.

A calcium atom is larger than a magnesium atom.

Explain why calcium reacts more vigorously than magnesium with hydrochloric acid of the same concentration.

This question is about acids and alkalis.

Acids and alkalis are substances that produce ions in aqueous solution. Draw one line from each substance to the ion always produced by that substance in aqueous solution.

Ion always produced in

What type of aqueous solution has a pH of 11? Tick (✓) one box.

A student determined the reacting volumes of hydrochloric acid and sodium hydroxide solution by titration. This is the method used.

1. Measure 25.0 cm³ of the sodium hydroxide solution.

2. Add the sodium hydroxide solution to a conical flask.

3. Add 3 drops of indicator to the sodium hydroxide solution.

4. Add the hydrochloric acid drop by drop until the indicator changes colour.

5. Record the volume of the hydrochloric acid added.

6. Repeat steps 1 to 5 three more times.

Which piece of equipment should be used to measure 25.0 cm³ of the sodium hydroxide solution in step 1? Tick (✓) one box.

Which piece of equipment should be used to add the hydrochloric acid drop by drop in step 4? Tick (✓) one box.

Table 1 shows the results.

Which is the anomalous result in Table 1 ?

Suggest one reason for the anomalous result in Table 1.

The student used a solution of sodium hydroxide of concentration 4.00 g/dm³. Calculate the mass of sodium hydroxide in 25.0 cm³ of this solution.

This question is about acids and alkalis.

Ethanoic acid is a weak acid. What is meant by ‘weak acid’? Answer in terms of ionisation.

The concentration of an acid can be measured in mol/dm³. Which combination of changes increases the concentration of an acid? Tick (✓) one box.

The concentration of an acid can be determined by titration. An indicator is added to an alkali in a flask.

Name an indicator that can be used in this titration. Give the colour change of the indicator when acid from a burette is added to the alkali in the flask.

Sodium carbonate dissolves in water to produce an alkaline solution. Give the formula of the ion that makes a solution alkaline.

A student does a titration using sodium carbonate solution and nitric acid. The equation for the reaction is:

25.0 cm³ of 0.124 mol/dm³ sodium carbonate solution is neutralised by

Calculate the concentration of the nitric acid. Give your answer to 3 significant figures. You should calculate:

• the number of moles of sodium carbonate in 25.0 cm³ of the solution

• the number of moles of nitric acid in 23.6 cm³ of the nitric acid

• the concentration of the nitric acid in mol/dm³.

When hydrochloric acid dissolves in water, hydrogen ions (H⁺) and chloride ions (Cl⁻) are produced.

A solution of hydrochloric acid with pH 4.5 has a concentration of H⁺ ions of

What is the concentration of H⁺ ions in a solution of hydrochloric acid with pH 2.5?

Which element has atoms that have the same electronic structure as the chloride ion? Use the periodic table.

This question is about acids.

A student added four metals, A, B, C and D to hydrochloric acid.

Figure 4 shows the rate of bubbling in each tube.

Use Figure 4 to answer questions 03.1 and 03.2.

Which metal is copper?

Tick (✓) one box.

Which metal is the most reactive?

Tick (✓) one box.

A metal oxide reacts with an acid to produce zinc sulfate and water.

Name the metal oxide and the acid used in this reaction.

Name of metal oxide

A student reacts an acid with an alkali in a titration.

What is the type of reaction when an acid reacts with an alkali?

Tick (✓) one box.

This question is about carbon and compounds of carbon.

Figure 9 shows diagrams that represent different structures.

Use Figure 9 to answer questions 06.1 and 06.2.

Which diagram represents graphite?

Tick (✓) one box.

Which diagram represents poly(ethene)?

Tick (✓) one box.

Figure 10 represents the structure of diamond.

How many covalent bonds does each carbon atom form in diamond?

Which is a property of diamond?

Tick (✓) one box.

Figure 11 shows a model of a molecule.

Complete the molecular formula of the molecule.

Molecular formula = C__ H__

Carbonic acid is a compound of carbon.

The formula of carbonic acid is H₂CO₃

Which ion is produced by carbonic acid in aqueous solution?

Tick (✓) one box.

Calculate the relative formula mass (M_r) of carbonic acid (H₂CO₃).

Relative atomic masses (A_r): H = 1 C = 12 O = 16

This question is about acids and alkalis.

Which ion do acids produce in aqueous solution?

Tick (✓) one box.

Acids react with alkalis.

What is the name of this type of reaction?

Tick (✓) one box.

Balance the equation for the reaction between sulfuric acid and potassium hydroxide.

Universal indicator turns purple in potassium hydroxide solution.

What is the pH of the solution?

Tick (✓) one box.

A student does a titration to find the volume of sulfuric acid that reacts with 25 cm³ of potassium hydroxide solution.

Figure 7 shows the equipment used.

The 25 cm³ of potassium hydroxide solution is measured with the measuring cylinder.

Which piece of equipment could the student use to measure the 25 cm³ of potassium hydroxide solution more accurately?

Tick (✓) one box.

Describe how the student would use the equipment in Figure 7 to complete the titration.

This question is about acids, bases and salts.

Zinc nitrate is a salt. A student produces zinc nitrate using an acid and a base.

Which acid should the student use to produce zinc nitrate? Tick (✓) one box.

Which is a base the student could use to produce zinc nitrate? Tick (✓) one box.

Name the salt with the formula MgBr₂

A student investigated how pH changes during a titration. This is the method used.

1. Pour 25.0 cm³ of hydrochloric acid into a beaker.

2. Measure the pH of the hydrochloric acid with a pH probe.

3. Add 1.0 cm³ of sodium hydroxide solution from a burette.

4. Swirl the mixture.

5. Measure the pH of the mixture.

6. Repeat steps 3 to 5 until a total of 30.0 cm³ of sodium hydroxide solution has been added.

Figure 10 shows the student’s results.

Describe how the pH of the mixture changes as sodium hydroxide solution is added to hydrochloric acid. Use data from Figure 10 in your answer.

What volume of sodium hydroxide solution is needed to neutralise 25.0 cm³ of hydrochloric acid? Use Figure 10.

Figure 11 shows the colour of universal indicator at different pH values.

The student could have used universal indicator instead of a pH probe. Determine the colour of universal indicator when 10.0 cm³ of sodium hydroxide solution has been added to 25.0 cm³ of hydrochloric acid. Use Figure 10 and Figure 11.

The student used a pipette to measure 25.0 cm³ of hydrochloric acid. Figure 12 shows a pipette.

Calculate the percentage uncertainty in the volume measured using this pipette. Use the equation:

Give one advantage of using a pipette rather than using a measuring cylinder to measure the volume of hydrochloric acid.

This question is about acids and alkalis.

Which ion do all acids produce in aqueous solution? Tick (✓) one box.

Calcium hydroxide solution reacts with an acid to form calcium chloride. Complete the word equation for the reaction.

A student investigates the volume of sodium hydroxide solution that reacts with 25.0 cm³ of dilute sulfuric acid. Figure 12 shows the apparatus the student uses.

Use Figure 12 to answer Questions 09.3 and 09.4

Name apparatus A.

What is the reading on apparatus A ?

The higher the concentration of a sample of dilute sulfuric acid, the greater the volume of sodium hydroxide needed to neutralise the acid. The student tested two samples of dilute sulfuric acid, P and Q. Describe how the student could use titrations to find which sample, P or Q, is more concentrated.

This question is about acids and alkalis.

Which ion do all acids produce in aqueous solution? Tick (✓) one box.

Calcium hydroxide solution reacts with an acid to form calcium chloride. Complete the word equation for the reaction.

A student investigates the volume of sodium hydroxide solution that reacts with 25.0 cm³ of dilute sulfuric acid. Figure 2 shows the apparatus the student uses.

Use Figure 2 to answer Questions 02.3 and 02.4

Name apparatus A.

What is the reading on apparatus A ?

The higher the concentration of a sample of dilute sulfuric acid, the greater the volume of sodium hydroxide needed to neutralise the acid. The student tested two samples of dilute sulfuric acid, P and Q. Describe how the student could use titrations to find which sample, P or Q, is more concentrated.

This question is about elements in Group 1.

A teacher burns sodium in oxygen.

What is the name of this type of reaction?

Tick one box.

The teacher dissolves the product of the reaction in water and adds universal indicator.

The universal indicator turns purple.

What is the pH value of the solution?

Tick one box.

The solution contains a substance with the formula NaOH

Give the name of the substance.

All alkalis contain the same ion.

What is the formula of this ion?

Tick one box.

A solution of NaOH had a concentration of 40 g/dm³

What mass of NaOH would there be in 250 cm³ of the solution?

The melting points of the elements in Group 1 show a trend.

Table 6 shows the atomic numbers and melting points of the Group 1 elements.

Plot the data from Table 6 on Figure 11.

Predict the melting point, X, of rubidium, atomic number 37

Use Figure 11.