A student planned an experiment to find out which substance would produce the biggest temperature decrease when added to either water or an acid. The chemicals she had access to were: ammonium nitrate solid sodium hydroxide solution citric acid solution sodium hydrogen carbonate solution water dilute hydrochloric acid How would you improve this method.

To determine the biggest temperature decrease, a suitable apparatus, laboratory thermometer must be used. Dissolution of solid ammonium nitrate in water shows the temperature difference of 19 ° C and the reaction between Sodium hydrogen carbonate reacts with citric acid shows the temperature difference of 5 ° C . Hence, dissolution of solid ammonium nitrate in water has the biggest temperature decrease.

Jonathan carried out an experiment to measure the temperature change when two solutions are mixed. His results are shown below. Reaction Temperature, t 1 ° C at start Temperature, t 2 ° C at end Sodium hydrogen carbonate solution + Citric acid 21 18 Sodium hydroxide solution + Citric acid 21 23 Dilute hydrochloric acid + Citric acid solution 21 21 State one variable that Jonathan should have controlled in this experiment.

A controlled experimental variable is a quantity that does not change in value during an experiment. These may affect the outcome and make it an unfair test. In this experiment, Jonathan should have controlled stirring of the mixture.

Jonathan carried out an experiment to measure the temperature change when two solutions are mixed. His results are shown below. Reaction Temperature t 1 , at start ° C Temperature t 2 , at end ° C Sodium hydrogen carbonate solution + Citric acid 21 18 Sodium hydroxide solution + Citric acid 21 23 Dilute hydrochloric acid + Citric acid solution 21 21 Which one of these reactions would be the most suitable for use in making an instant cold pack? Explain your answer.

To make an instant cold pack, the reaction must be endothermic. In such reaction, heat energy is absorbed from the surroundings. Hence, the most suitable mixture for use in making an instant cold pack is a mixture of Sodium hydrogen carbonate and Citric acid. In this mixture t 2 < t 1 . Hence, it is endothermic.

Jonathan carried out an experiment to measure the temperature change when two solutions are mixed. His results are shown below. Reaction Temperature t 1 , at start ° C Temperature t 2 , at end ° C Sodium hydrogen carbonate solution + Citric acid 21 18 Sodium hydroxide solution + Citric acid 21 23 Dilute hydrochloric acid + Citric acid solution 21 21 What type of the reaction is second reaction?

In the reaction between Sodium hydroxide and Citrus acid, t 2 > t 1 , i.e., the final temperature is slightly greater than initial temperature. Hence, it is an exothermic reaction. In such reaction, heat energy is liberated to the surroundings.

The diagram shows the particles in a liquid that is evaporating. Explain why evaporation causes the temperature of the liquid to decrease?

Evaporation is conversion of liquid to gaseous form below its boiling point. It is an endothermic process. As the temperature increases, the kinetic energy of molecules also increases. It is proportional to temperature. As the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid decreases.

Lucy Hawkins, Fran Eardley, Stuart Lloyd and, Gemma Young Solutions for Chapter: Energy Transfers in Chemistry, Exercise 12: End of Chapter Review

Author:Lucy Hawkins, Fran Eardley, Stuart Lloyd & Gemma Young

Lucy Hawkins Science Solutions for Exercise - Lucy Hawkins, Fran Eardley, Stuart Lloyd and, Gemma Young Solutions for Chapter: Energy Transfers in Chemistry, Exercise 12: End of Chapter Review

Attempt the free practice questions on Chapter 8: Energy Transfers in Chemistry, Exercise 12: End of Chapter Review with hints and solutions to strengthen your understanding. Cambridge Lower Secondary Science Stage 9: Student's Book solutions are prepared by Experienced Embibe Experts.

Questions from Lucy Hawkins, Fran Eardley, Stuart Lloyd and, Gemma Young Solutions for Chapter: Energy Transfers in Chemistry, Exercise 12: End of Chapter Review with Hints & Solutions

EASY

Lower Secondary Stage 9

IMPORTANT

Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 5

Name the process that occurs when the fast moving particles in a liquid escape from its surface.

MEDIUM

Lower Secondary Stage 9

IMPORTANT

Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 9

Instant cold packs can be made using ammonium nitrate and water. The pack contains a small bag of solid ammonium nitrate. This bag is inside another bag, which is full of water. When you squeeze the outer bag the smaller bag bursts. The ammonium nitrate dissolves in water and the pack becomes cold.

Explain how you know this.

MEDIUM

Lower Secondary Stage 9

IMPORTANT

Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 10

A student planned an experiment to find out which substance would produce the biggest temperature decrease when added to either water or an acid. The chemicals she had access to were:

ammonium nitrate solid
sodium hydroxide solution
citric acid solution
sodium hydrogen carbonate solution
water
dilute hydrochloric acid

How would you improve this method.

MEDIUM

Lower Secondary Stage 9

IMPORTANT

Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 11

Jonathan carried out an experiment to measure the temperature change when two solutions are mixed. His results are shown below.

Reaction	Temperature, $t_{1} ° C$ at start	Temperature, $t_{2} ° C$ at end
Sodium hydrogen carbonate solution + Citric acid	$21$	$18$
Sodium hydroxide solution + Citric acid	$21$	$23$
Dilute hydrochloric acid + Citric acid solution	$21$	$21$

State one variable that Jonathan should have controlled in this experiment.

MEDIUM

Lower Secondary Stage 9

IMPORTANT

Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 11

Jonathan carried out an experiment to measure the temperature change when two solutions are mixed. His results are shown below.

Reaction	Temperature $t_{1}$ , at start $(° C)$	Temperature $t_{2}$ , at end $(° C)$
Sodium hydrogen carbonate solution + Citric acid	$21$	$18$
Sodium hydroxide solution + Citric acid	$21$	$23$
Dilute hydrochloric acid + Citric acid solution	$21$	$21$

Which one of these reactions would be the most suitable for use in making an instant cold pack? Explain your answer.

EASY

Lower Secondary Stage 9

IMPORTANT

Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 11

Jonathan carried out an experiment to measure the temperature change when two solutions are mixed. His results are shown below.

Reaction	Temperature $t_{1}$ , at start $(° C)$	Temperature $t_{2}$ , at end $(° C)$
Sodium hydrogen carbonate solution + Citric acid	$21$	$18$
Sodium hydroxide solution + Citric acid	$21$	$23$
Dilute hydrochloric acid + Citric acid solution	$21$	$21$

What type of the reaction is second reaction?

MEDIUM

Lower Secondary Stage 9

IMPORTANT

Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 12

The diagram shows the particles in a liquid that is evaporating.

Question Image

Explain why evaporation causes the temperature of the liquid to decrease?

MEDIUM

Lower Secondary Stage 9

IMPORTANT

Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 12

The diagram shows the particles in a liquid that is evaporating.

Question Image

Wet clothes dry because water evaporates from them. Describe one change in the weather that would cause clothes to dry faster.

Lucy Hawkins, Fran Eardley, Stuart Lloyd and, Gemma Young Solutions for Chapter: Energy Transfers in Chemistry, Exercise 12: End of Chapter Review

Lucy Hawkins Science Solutions for Exercise - Lucy Hawkins, Fran Eardley, Stuart Lloyd and, Gemma Young Solutions for Chapter: Energy Transfers in Chemistry, Exercise 12: End of Chapter Review

Questions from Lucy Hawkins, Fran Eardley, Stuart Lloyd and, Gemma Young Solutions for Chapter: Energy Transfers in Chemistry, Exercise 12: End of Chapter Review with Hints & Solutions

Learn and Prepare for any exam you want !