Collision theory and activation energy

This question is about temperature changes.

A student investigated the temperature changes as solids are dissolved in water.

This is the method used.

1. Measure 100 cm³ of water into a polystyrene cup.

2. Measure the temperature of the water.

3. Add 5.0 g of solid copper sulfate to the water.

4. Stir the mixture until all the copper sulfate has dissolved.

5. Measure the highest temperature reached by the mixture.

6. Repeat steps 1 to 5 with solid lithium chloride.

Draw one line from each measurement to the piece of equipment used to make the measurement.

Table 2 shows the highest temperature reached for each solid when dissolved in water.

Complete Figure 14.

You should:

use a suitable scale for the y-axis

plot the data for lithium chloride from Table 2 as a bar chart.

Before solid copper sulfate was added, the temperature of the water was 17 °C.

How do the results in Table 2 show that the process was exothermic?

The student used a different method to measure the temperature change when solid calcium chloride dissolved in water.

The student did four tests.

Table 3 shows the results.

Calculate mean value X in Table 3.

Figure 15 shows a reaction profile.

Which label on Figure 15 represents the products?

Tick () one box.

A B C D

Which label on Figure 15 represents the activation energy?

Tick () one box.

A B C D

Which label on Figure 15 represents the overall energy change?

Tick () one box.

A B C D

The elements in Group 1 of the periodic table are called the alkali metals.

Lithium reacts with chlorine to produce lithium chloride.

Figure 11 shows the reaction profile for the reaction between lithium and chlorine.

What do labels A, B and C on Figure 11 represent?

What type of reaction does the reaction profile in Figure 11 represent?

Describe what happens when a lithium atom reacts with a chlorine atom.

Answer in terms of electrons.

Explain the trend in the reactivity of the Group 1 metals.

A student investigated the rate of the reaction between calcium carbonate and hydrochloric acid.

The word equation for the reaction is:

calcium carbonate + hydrochloric acid calcium chloride + water + carbon dioxide

Figure 6 shows the apparatus.

This is the method used.

1. Add 50 cm³ of hydrochloric acid to the conical flask.

2. Add 2.0 g of calcium carbonate to the conical flask.

3. Immediately insert the stopper into the conical flask and start the timer.

4. Record the volume of gas collected in the gas syringe every 30 seconds.

5. Stop recording when the volume of gas in the gas syringe does not change.

Which piece of equipment is the most suitable to measure the volume of hydrochloric acid?

Tick (✓) one box.

Beaker

Measuring cylinder

Test tube

Name one piece of equipment that can be used to measure the mass of calcium carbonate.

Why must the stopper be inserted immediately after the reactants are added to the flask?

Figure 7 shows the results.

Describe the trend for the volume of gas collected.

Use Figure 7.

Determine the mean rate of reaction from 0 to 30 seconds.

Use Figure 7.

Use the equation:

Choose the unit from the box.

What is the minimum amount of energy that particles must have to react?

Tick (✓) one box.

Activation energy

Kinetic energy

Potential energy

Hydrogen bromide decomposes to form hydrogen and bromine.

The equation for the reaction is:

The energy needed to break the existing bonds is 103 kJ/mol greater than the energy released in forming new bonds.

Table 3 shows some bond energy values.

Y is the bond energy of a H–Br bond.

Calculate Y.

_ Y = _________________ kJ/mol

Figure 12 shows part of the reaction profile when hydrogen bromide decomposes to form hydrogen and bromine.

Complete Figure 12.

You should: label the axes draw the reaction profile label the reactant and the products label the activation energy.

This question is about metals reacting with oxygen.

Calcium (Ca) reacts with oxygen (O₂) to produce calcium oxide (CaO).

Balance the equation for the reaction.

______ Ca + O₂ → 2 CaO

40 g of calcium reacts completely with oxygen to produce 56 g of calcium oxide.

Calculate the maximum mass of calcium oxide that could be produced from 10 g of calcium.

A student reacted different masses of magnesium with oxygen and measured the mass of magnesium oxide produced.

Figure 3 shows the results.

Why did the student ignore one of the points when drawing the line of best fit on Figure 3 ?

Predict the mass of magnesium oxide produced from 0.5 g of magnesium.

You should extend the line of best fit on Figure 3.

A different student reacted copper with oxygen and measured the mass of copper oxide produced.

The student did repeat measurements for each mass of copper.

Table 1 shows the results when 0.42 g of copper was reacted.

Calculate mean value X in Table 1.

The reaction between copper and oxygen is exothermic.

Which reaction profile represents this reaction?

Tick (✓) one box.

This question is about the reaction between hydrochloric acid and sodium hydroxide solution.

A student investigated the effect of changing the volume of sodium hydroxide solution on the temperature change during the reaction.

This is the method used.

1. Measure 30 cm³ of hydrochloric acid into a polystyrene cup.

2. Measure the temperature of the hydrochloric acid.

3. Add 5 cm³ of sodium hydroxide solution.

4. Stir the mixture.

5. Measure the highest temperature the mixture reaches.

6. Repeat steps 1 to 5 three more times and calculate the mean temperature change.

7. Repeat steps 1 to 6 with different volumes of sodium hydroxide solution.

What two pieces of equipment should be used in this investigation?

Tick (✓) two boxes.

Balance

Measuring cylinder

Ruler

Stopclock

Thermometer

Table 1 shows the results for one volume of sodium hydroxide solution.

Calculate value X in Table 1.

Which type of error is reduced by repeating the tests and calculating the mean?

Tick (✓) one box.

Random

Systematic

Zero

A different student did the same investigation.

Figure 2 shows the results.

What was the mean temperature change when the volume of sodium hydroxide solution was 15 cm³?

Use Figure 2.

Give one conclusion from the results in Figure 2.

The reaction between hydrochloric acid and sodium hydroxide is exothermic.

Exothermic reactions give out energy.

Which reaction profile shows an exothermic reaction?

Tick (✓) one box.

Calculate the relative formula mass (M_r) of sodium hydroxide (NaOH).

Relative atomic masses (A_r): Na = 23 O = 16 H = 1

This question is about hydrocarbons.

When a hydrocarbon C₁₀H₂₂ is cracked, two substances are produced.

Complete the equation for the reaction.

Explain why the hydrocarbon C₇H₁₆ has a lower boiling point than C₁₀H₂₂

Ethanol is produced by reacting ethene with steam.

The equation for the reaction is:

Figure 4 shows the percentage yield of ethanol using different reaction conditions.

Explain why changing the pressure affects the percentage yield of ethanol.

The forward reaction is exothermic.

How does Figure 4 provide evidence for this?

Figure 5 shows part of a reaction profile diagram.

A catalyst is used in the reaction to produce ethanol.

Complete Figure 5 to show how the catalyst increases the rate of this reaction.

You should label the reaction profile diagram.

Suggest why the catalyst does not affect the yield of ethanol at equilibrium.

This question is about hydrogen chloride.

A hydrogen atom contains 1 electron and a chlorine atom contains 17 electrons.

Complete Figure 7 to show a dot and cross diagram for a hydrogen chloride molecule.

Show the outer electrons only.

Hydrogen gas (H₂) reacts with chlorine gas to produce hydrogen chloride.

Complete the balanced chemical equation for the reaction between hydrogen and chlorine.

Figure 8 shows the reaction profile diagram for the reaction between hydrogen and chlorine.

What do A and B represent on Figure 8 ?

How does the reaction profile diagram show that the reaction is exothermic?

Hydrogen chloride gas dissolves in water to form hydrochloric acid.

Hydrochloric acid contains hydrogen ions and chloride ions.

Explain why hydrogen chloride gas does not conduct electricity but hydrochloric acid is able to conduct electricity.

This question is about hydrogen chloride.

A hydrogen atom contains 1 electron and a chlorine atom contains 17 electrons.

Complete Figure 1 to show a dot and cross diagram for a hydrogen chloride molecule.

Show the outer electrons only.

Hydrogen gas (H₂) reacts with chlorine gas to produce hydrogen chloride.

Complete the balanced chemical equation for the reaction between hydrogen and chlorine.

Figure 2 shows the reaction profile diagram for the reaction between hydrogen and chlorine.

What do A and B represent on Figure 2 ?

How does the reaction profile diagram show that the reaction is exothermic?

Hydrogen chloride gas dissolves in water to form hydrochloric acid.

Hydrochloric acid contains hydrogen ions and chloride ions.

Explain why hydrogen chloride gas does not conduct electricity but hydrochloric acid is able to conduct electricity.