C5 Energy Changes

Last updated 6 days ago

33 Nsɛmmisa

4.5.1.1 Energy transfer during exothermic and endothermic reactions

4.5.1.1

MS2b

WS3.7

4.4.1.2

4.5.1.1

WS3.5

WS4.1

WS3.5

WS3.8

4.5.1.1

MS2b

4.5.1.1

4.5.1.3

4.5.1.1

WS2.6

4.5.1.2 Reaction profiles

4.5.1.2

4.5.1.3 The energy change of reactions

4.5.2.1 Cells and batteries

4.5.2.1

4.5.2.2 Fuel cells

4.5.2.2

C5 Energy Changes

Last updated 6 days ago

33 Nsɛmmisa

4.5.1.1 Energy transfer during exothermic and endothermic reactions

What happens to energy in an endothermic reaction?

Energy stays the same throughout the reaction.

Energy is released into the surroundings.

Energy transforms into a different type.

Energy is absorbed from the surroundings.

4.5.1.1

In an endothermic reaction, how does the temperature change?

The reaction has no temperature change.

The temperature s increases.

The temperature decreases.

4.5.1.1

Which 2 of these are examples of endothermic reactions?

4.5.1.1

What do exothermic reactions release during the reaction?

Energy in the form of heat

Solid products only

Energy in the form of light

Electricity for powering devices

4.5.1.1

In an exothermic reaction, how does the temperature change?

Temperature remains the same

The temperature increases.

The temperature decreases

4.5.1.1

Which 2 of these are examples of exothermic reactions?

4.5.1.1

A reaction where the surrounding temperature decreases. Is this an exo or endothermic reaction?

Neither

Both

Endothermic reaction

Exothermic reaction

4.5.1.1

An ice cube is melting on a warm day. Is this an exo or endothermic reaction?

Both

Neither

Exothermic reaction

Endothermic reaction

4.5.1.1

You feel heat when adding water to a chemical heat pack. Is this an exo or endothermic reaction?

Both

Exothermic reaction

Neither

Endothermic reaction

4.5.1.1

A chemical reaction that increases the outside temperature. Is it an exo or an endothermic reaction?

Both

Endothermic reaction

Neither

Exothermic reaction

4.5.1.1

A student investigated the reactivity of metals with hydrochloric acid.This is the method used.
1. Measure 50 cm3 of hydrochloric acid into a polystyrene cup.
2. Measure the temperature of the hydrochloric acid.
3. Add one spatula of metal powder to the hydrochloric acid and stir.
4. Measure the highest temperature the mixture reaches.
5. Calculate the temperature increase for the reaction.
6. Repeat steps 1 to 5 three more times.
7. Repeat steps 1 to 6 with different metals.
The table below shows the student’s results.
Calculate the mean temperature increase X for magnesium in the table above.
Do not include the anomalous result in your calculation.

MS2b

WS3.7

4.4.1.2

4.5.1.1

WS3.5

From above, What type of variable is the volume of hydrochloric acid in this investigation?

Control

Dependent

Independent

WS4.1

A student investigated the temperature change when zinc reacts with copper sulfate solution.
The student used a different concentration of copper sulfate solution for each experiment.The student used the apparatus shown below.
The student:
•        measured 50 cm3 copper sulfate solution into a glass beaker
•        measured the temperature of the copper sulfate solution
•        added 2.3 g zinc
•        measured the highest temperature
•        repeated the experiment using copper sulfate solution with different concentrations.
The equation for the reaction is:
Zn(s)     +                 CuSO4(aq)               -->     Cu(s)       +              ZnSO4(aq)
zinc       +      copper sulfate solution    -->    copper      +    zinc sulfate solution
The student’s results are shown in the table below.
Describe and explain the trends shown in the student’s results.

WS3.5

WS3.8

4.5.1.1

The decomposition of hydrogen peroxide gives out energy to the surroundings
What type of reaction is this?

Displacement

Endothermic

Exothermic

Neutralisation

4.5.1.1

Calculate the mean of the temperature change results. Do NOT use anomalies.

4.5.1.1

MS2b

A student is given three metals, X, Y and Z to identify.
The metals are magnesium, iron and copper.
Plan an investigation to identify the three metals by comparing their reactions with dilute hydrochloric acid.
Your plan should give valid results.

4.5.1.1

4.5.1.3

Complete the table

4.5.1.1

WS2.6

4.5.1.2 Reaction profiles

Endo or exo?

Endothermic

Exothermic

4.5.1.2

Endo or exo?

Endothermic

Exothermic

4.5.1.2

Endo or exo?

Endothermic

Exothermic

4.5.1.2

Endo or exo?

Endothermic

Exothermic

4.5.1.2

• draw the reaction profile
• draw an arrow to show the overall energy change (label this E)
• draw an arrow to show the activation energy (label this A)
CH₄ + H₂O → CO + 3H₂
Energy change = +208 kJ/mol

4.5.1.2

What is the energy change of this reaction?

4.5.1.2

• draw the reaction profile
• draw an arrow to show the overall energy change (label this E)
• draw an arrow to show the activation energy (label this A)
3H₂ + N₂ → 2NH₃
Energy change = –76 kJ/mol

4.5.1.2

4.5.1.3 The energy change of reactions

4.5.2.1 Cells and batteries

In a chemical cell, also called a voltaic cell, the substance that is most easily

oxidised will give up its electrons to the external circuit and is the anode of the cell.

The voltage produced by an electric cell depends on....

The type of electrodes

The difference in reactivity of the metal electrodes

The reading on the voltmeter

The type of electrolyte

4.5.2.1

Which of the follow combinations of metals would make an electric cell with the greatest voltage?

Magnesium and iron

Magnesium and copper

Magnesium and lead

4.5.2.1

In an electric cell made from magnesium and copper, the magnesium pushes the electrons around the circuit

Nokorɛ

Ɛnyɛ ampa

4.5.2.1

Which of the following are advantages of using a lithium-ion battery?

They release toxic chemical on disposal

They can catch fire

They are made from materials that can be recycled when they are no longer rechargeable

They can be recharged many times

4.5.2.1

4.5.2.2 Fuel cells

4.5.2.2

Why is the chemical reaction between oxygen and hydrogen used in a fuel cell?

to produce a voltage

to produce water

4.5.2.2

Label this hydrogen fuel cell

Mmuae Afoforo a Wobɛpaw:

Oxygen

Electrolyte

Hydrogen

Cathode

Anode

Water

4.5.2.2

C5 Energy Changes

C5 Energy Changes

What happens to energy in an endothermic reaction?

In an endothermic reaction, how does the temperature change?

Which 2 of these are examples of endothermic reactions?

What do exothermic reactions release during the reaction?

In an exothermic reaction, how does the temperature change?

Which 2 of these are examples of exothermic reactions?

A reaction where the surrounding temperature decreases. Is this an exo or endothermic reaction?

An ice cube is melting on a warm day. Is this an exo or endothermic reaction?

You feel heat when adding water to a chemical heat pack. Is this an exo or endothermic reaction?

A chemical reaction that increases the outside temperature. Is it an exo or an endothermic reaction?

From above, What type of variable is the volume of hydrochloric acid in this investigation?

The decomposition of hydrogen peroxide gives out energy to the surroundingsWhat type of reaction is this?

Calculate the mean of the temperature change results. Do NOT use anomalies.

A student is given three metals, X, Y and Z to identify. The metals are magnesium, iron and copper. Plan an investigation to identify the three metals by comparing their reactions with dilute hydrochloric acid. Your plan should give valid results.

Complete the table

Endo or exo?

Endo or exo?

Endo or exo?

Endo or exo?

• draw the reaction profile • draw an arrow to show the overall energy change (label this E) • draw an arrow to show the activation energy (label this A) CH4 + H2O → CO + 3H2 Energy change = +208 kJ/mol

What is the energy change of this reaction?

• draw the reaction profile • draw an arrow to show the overall energy change (label this E) • draw an arrow to show the activation energy (label this A) 3H2 + N2 → 2NH3 Energy change = –76 kJ/mol

The voltage produced by an electric cell depends on....

Which of the follow combinations of metals would make an electric cell with the greatest voltage?

In an electric cell made from magnesium and copper, the magnesium pushes the electrons around the circuit

Which of the following are advantages of using a lithium-ion battery?

Why is the chemical reaction between oxygen and hydrogen used in a fuel cell?

What happens to energy in an endothermic reaction?

In an endothermic reaction, how does the temperature change?

Which 2 of these are examples of endothermic reactions?

What do exothermic reactions release during the reaction?

In an exothermic reaction, how does the temperature change?

Which 2 of these are examples of exothermic reactions?

A reaction where the surrounding temperature decreases. Is this an exo or endothermic reaction?

An ice cube is melting on a warm day. Is this an exo or endothermic reaction?

You feel heat when adding water to a chemical heat pack. Is this an exo or endothermic reaction?

A chemical reaction that increases the outside temperature. Is it an exo or an endothermic reaction?

From above, What type of variable is the volume of hydrochloric acid in this investigation?

The decomposition of hydrogen peroxide gives out energy to the surroundingsWhat type of reaction is this?

Calculate the mean of the temperature change results. Do NOT use anomalies.

A student is given three metals, X, Y and Z to identify. The metals are magnesium, iron and copper. Plan an investigation to identify the three metals by comparing their reactions with dilute hydrochloric acid. Your plan should give valid results.

Complete the table

Endo or exo?

Endo or exo?

Endo or exo?

Endo or exo?

• draw the reaction profile • draw an arrow to show the overall energy change (label this E) • draw an arrow to show the activation energy (label this A) CH4 + H2O → CO + 3H2 Energy change = +208 kJ/mol

What is the energy change of this reaction?

• draw the reaction profile • draw an arrow to show the overall energy change (label this E) • draw an arrow to show the activation energy (label this A) 3H2 + N2 → 2NH3 Energy change = –76 kJ/mol

The voltage produced by an electric cell depends on....

Which of the follow combinations of metals would make an electric cell with the greatest voltage?

In an electric cell made from magnesium and copper, the magnesium pushes the electrons around the circuit

Which of the following are advantages of using a lithium-ion battery?

Why is the chemical reaction between oxygen and hydrogen used in a fuel cell?

The decomposition of hydrogen peroxide gives out energy to the surroundings
What type of reaction is this?

A student is given three metals, X, Y and Z to identify.
The metals are magnesium, iron and copper.
Plan an investigation to identify the three metals by comparing their reactions with dilute hydrochloric acid.
Your plan should give valid results.

• draw the reaction profile
• draw an arrow to show the overall energy change (label this E)
• draw an arrow to show the activation energy (label this A)
CH₄ + H₂O → CO + 3H₂
Energy change = +208 kJ/mol

• draw the reaction profile
• draw an arrow to show the overall energy change (label this E)
• draw an arrow to show the activation energy (label this A)
3H₂ + N₂ → 2NH₃
Energy change = –76 kJ/mol

The decomposition of hydrogen peroxide gives out energy to the surroundings
What type of reaction is this?

A student is given three metals, X, Y and Z to identify.
The metals are magnesium, iron and copper.
Plan an investigation to identify the three metals by comparing their reactions with dilute hydrochloric acid.
Your plan should give valid results.

• draw the reaction profile
• draw an arrow to show the overall energy change (label this E)
• draw an arrow to show the activation energy (label this A)
CH₄ + H₂O → CO + 3H₂
Energy change = +208 kJ/mol

• draw the reaction profile
• draw an arrow to show the overall energy change (label this E)
• draw an arrow to show the activation energy (label this A)
3H₂ + N₂ → 2NH₃
Energy change = –76 kJ/mol