Reactivity of metals

A student investigated the reaction of magnesium with oxygen.

Figure 6 shows the apparatus.

This is the method used.

1. Measure the mass of an empty crucible.

2. Add 0.10 g of magnesium to the crucible.

3. Heat the crucible and contents for 5 minutes.

4. Allow to cool and measure the mass of the crucible and contents.

5. Repeat steps 1 to 4 using different masses of magnesium.

Complete the word equation for the reaction.

magnesium + oxygen →

Complete the sentence.

Choose the answer from the box.

Table 3 shows the measurements for one of the experiments.

Calculate the mass of magnesium in the crucible before heating.

Why does the reaction result in an increase in the mass of the contents of the crucible?

Tick () one box.

The student determined the mass of the contents of the crucible after heating each mass of magnesium.

Figure 7 shows the results.

Draw a ring around the anomalous result in Figure 7.

The student did the experiment using 0.60 g of magnesium four times.

Table 4 shows the results.

Calculate mean value X.

The student used a Bunsen burner instead of a water bath to heat the crucible.

Why did the student use a Bunsen burner?

Tick () one box.

A different student did the investigation.

The student heated the crucible for 1 minute instead of for 5 minutes.

The student obtained different results.

Suggest one reason why the student obtained different results.

Magnesium chloride is a soluble salt.

Magnesium reacts with hydrochloric acid to produce magnesium chloride and a gas.

Which gas is produced?

Tick () one box.

Magnesium chloride (MgCl₂) can be electrolysed when molten.

Tick () one box.

Magnesium chloride contains Mg²⁺ ions and Cl^– ions.

Name the product at each electrode when molten magnesium chloride is electrolysed.

A student investigated the reactivity of three metals: copper, magnesium and iron.

The student mixed each metal with each metal chloride solution.

Table 6 shows the results.

What is the order of reactivity for copper, magnesium and iron?

Give two reasons for your answer.

Use Table 6.

When heated 0.72 g of magnesium reacts with iron oxide to produce 2.32 g of products.

Calculate the mass of iron oxide that reacts with 0.72 g of magnesium.

A student investigated the temperature change when magnesium was added to zinc sulfate solution. Figure 5 shows the apparatus.

Which piece of equipment is labelled X ? Tick (✓) one box.

Which piece of equipment is the best to use to measure volumes of solution? Tick (✓) one box.

The student added 1.0 g of magnesium to 50 cm³ of zinc sulfate solution and

measured the temperature increase. The student repeated the experiment two more times. Table 1 shows the results.

Calculate value Y in Table 1.

The student then added 1.2 g of magnesium to 50 cm³ of zinc sulfate solution. The temperature increased by 9.0 °C. Calculate the temperature increase when the student adds 0.40 g of magnesium to 50 cm³ of zinc sulfate solution.

What is the name given to a reaction which causes the temperature to increase? Tick (✓) one box.

The student repeated the experiment with 1.2 g of copper and 50 cm³ of zinc sulfate solution. The temperature did not increase. Give one reason why.

Plan an investigation to find the order of reactivity of three metals. You should use the temperature change when each metal reacts with hydrochloric acid.

Plan an investigation to find the order of reactivity of three metals. You should use the temperature change when each metal reacts with hydrochloric acid.

This question is about hydrogen chloride and hydrochloric acid.

Complete the dot and cross diagram to represent the bonding in hydrogen chloride on Figure 7. Use dots (o) 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 is a strong acid. What is meant by the term strong acid?

Describe how magnesium can be used to distinguish between a strong acid and a weak acid of the same concentration.

The concentration of hydrochloric acid is increased by a factor of 100 What is the change in pH?

Ethene and hydrogen chloride react to produce chloroethane. The displayed formulae equation for the reaction is:

The reaction is exothermic. In the reaction the energy released forming new bonds is 56 kJ/mol greater than the energy needed to break existing bonds. Table 1 shows some bond energies.

Calculate the bond energy X.

A student investigated the temperature change when metal X was added to copper sulfate solution. This is the method used.

1. Add 25 cm³ of copper sulfate solution to a beaker.

2. Measure the temperature of the copper sulfate solution.

3. Add 1.0 g of metal X and stir.

4. Measure the highest temperature reached when metal X is added to copper sulfate solution.

5. Repeat steps 1 to 4 with different metals.

Figure 1 shows the apparatus used.

Figure 2 shows the thermometer reading of the copper sulfate solution at the start of the investigation.

The highest temperature reached when metal X was added to copper sulfate solution was 35.5 °C Determine the temperature change when metal X is added to copper sulfate solution. Use Figure 2. Highest temperature = 35.5 °C

Give two variables the student should keep the same in this investigation.

The student repeated the experiment with metal Y. Table 1 shows four results for metal Y.

Calculate the mean temperature change for metal Y. Do not include the anomalous result in your calculation.

The more reactive the metal added to copper sulfate solution, the greater the temperature change. Figure 3 shows a reactivity series.

Figure 3

Calcium Magnesium Zinc Copper Silver least reactive

The student repeated the experiment. The student added:

• magnesium to copper sulfate solution

• an unknown metal A to copper sulfate solution.

Table 2 shows the results.

The student concludes metal A is zinc. Give one reason why the student is correct. Use Figure 3 and Table 2.

The student did the experiment with silver and copper sulfate solution. What happens to the temperature of the mixture? Use Figure 3. Tick (✓) one box.

Suggest one reason why the student should not add potassium metal to copper sulfate solution.

100 cm³ of the copper sulfate solution contains 1.8 g of copper sulfate. Calculate the mass of copper sulfate in 25 cm³ of this copper sulfate solution.

A student investigated the temperature change when magnesium was added to copper sulfate solution. This is the method used.

1. Pour 30 cm³ of copper sulfate solution into a polystyrene cup.

2. Measure the temperature of copper sulfate solution every minute for 3 minutes.

3. Add magnesium on the fourth minute.

4. Measure the temperature of the mixture at 5 minutes and then every minute up to 14 minutes.

What is the dependent variable in this investigation?

The student used the results to plot a graph.

Figure 4 shows the graph.

Suggest why the copper sulfate solution was left for four minutes before adding the magnesium.

Complete Figure 4 by:

• drawing a line of best fit through all the points after 7 minutes

• extending the line back to 4 minutes.

The temperature change for the reaction is the temperature difference between the two graph lines at 4 minutes. Determine the temperature change for the reaction. Use Figure 4.

Explain why the temperature of the mixture decreases after 7 minutes.

The student repeated the experiment with an unknown metal Q instead of magnesium. All the other variables were kept the same. The student recorded a smaller temperature change. Suggest the identity of metal Q. Give one reason for your answer.

A copper sulfate solution contained 0.100 moles of copper sulfate dissolved

Calculate the mass of copper sulfate in 30.0 cm³ of this solution. Relative formula mass (M_r): CuSO₄ = 159.5

This question is about reactions of metals. Figure 7 shows what happens when calcium, copper, magnesium and zinc are added to hydrochloric acid.

What is the order of decreasing reactivity of these four metals? Tick (✓) one box.

A student wants to make a fair comparison of the reactivity of the metals with hydrochloric acid.

Name two variables that must be kept constant.

What is the independent variable in this reaction?

Predict the reactivity of beryllium compared with magnesium. Give a reason for your answer. Use the periodic table.

A solution of hydrochloric acid contains 3.2 g of hydrogen chloride in 50 cm³ Calculate the concentration of hydrogen chloride in g per dm³

This question is about reactions of metals. Figure 1 shows what happens when calcium, copper, magnesium and zinc are added to hydrochloric acid.

What is the order of decreasing reactivity of these four metals? Tick (✓) one box.

A student wants to make a fair comparison of the reactivity of the metals with hydrochloric acid.

Name two variables that must be kept constant.

What is the independent variable in this reaction?

Predict the reactivity of beryllium compared with magnesium. Give a reason for your answer. Use the periodic table.

A solution of hydrochloric acid contains 3.2 g of hydrogen chloride in 50 cm³ Calculate the concentration of hydrogen chloride in g per dm³