CHEMICAL REACTIONS Level E/F: Homework Sheets Chemical Reactions Homework Sheets Improving Science Education 5-14 (1999), section 2.3 makes the following statement about homework: Science homework was rarely given in primary schools and was not sufficiently purposeful or challenging in secondary schools. The following homework sheets are designed to address this need. The questions are intended to offer the opportunity for pupils to think, write extended answers and try some simple practical tasks. Teachers should ensure that pupils are given any necessary safety advice in relation to the practical tasks (e.g. do not drink the water after adding salt, if the tumbler breaks, ask an adult to help clean the broken glass). Although entitled Homework Sheets, these questions can be used to check pupils understanding and can be used in class as well as at home. The material supplied here is not exhaustive. Teachers can and should use other sources for homework in the course of their teaching. Glasgow 5-14 Science Programme Education Improvement Service 48
1 What happens in all chemical reactions? Describe a chemical reaction that you have seen. thermometer Janice reacted vinegar and chalk in a flask and measured how the temperature changed over a period of 10 minutes. bubbles of gas vinegar chalk Time (minutes) 1 2 3 4 5 6 7 8 9 10 Temperature ( C) 20 23 26 29 32 35 37 38 38 38 Draw a line graph of these results. Glasgow 5-14 Science Programme Education Improvement Service 49
2 1. For each of the following experiments state how you know a chemical reaction has taken place. Glasgow 5-14 Science Programme Education Improvement Service 50
3 1 (a) Look at the particles of the two different elements. Draw in the space below what they might look like if they became a compound. (b) The compound made is called magnesium oxide. What would be the names of the two elements used to make this compound? (c) What are compounds made from? 2 An enquiring scientist found three gas jars with sealed lids. He knew they contained three different gases but the labels has fallen off. The gas in jar A relit a glowing splint. The gas in jar B put out a burning taper with a pop. The gas in jar C turned lime water milky. Draw lines from the labels to the jars to show the gas present in each. Glasgow 5-14 Science Programme Education Improvement Service 51
CHEMICAL REACTIONS: Level F: Homework Sheet 4 1 Matthew wanted to find out which type of marble would produce 20 ml of gas the fastest when added to sulphuric acid. The time taken to produce the quantity of gas is shown for two of the reactions in the table below. Marble powdered Time taken to produce 20 ml of gas (s) 18 flaked chips 25 lump Complete the table to show the time that might be taken for the other two reactions to produce 20 ml of the gas. Which type of marble was the slowest to produce 20 ml of the gas? If 4g of powdered marble had been used instead of 2g, how long do you think it would have taken to produce 20 ml of the gas? 2. A pupil adds a lump of chalk to a beaker of acid, which reacts giving off bubbles of gas. What difference would he have seen if he had used powdered chalk instead of a lump? Glasgow 5-14 Science Programme Education Improvement Service 52
5 Ross decided to find out which concentration of acid dissolved eggshells fastest. He carried out the following steps but the order has been jumbled up. A. Time how long it takes the eggshells to dissolve. B. Measure 10 ml of the 1% acid into a boiling tube. C. Repeat the experiment wit theother three concentrations of acid. D. Compare the time taken for the acids to dissolve the eggshells. E. Add 0.5 grams of eggshells into the acid. Sort out the steps into the correct order to carry out the experiment, by writing the correct letter in the spaces below. The first step has been inserted for you. B First Second Third Fourth Fifth Here is the table of Ross s results. Concentration of acid 1% 5% 10% 2% Time taken to dissolve the eggshells (s) 90 55 35 75 Fill in the correct concentration of acid in the sentences below. was the fastest at dissolving eggshells. was the slowest at dissolving eggshells. Calculate the average time taken to dissolve the eggshells. seconds Glasgow 5-14 Science Programme Education Improvement Service 53
CHEMICAL REACTIONS: Level F: Homework Sheet 6 Put a tick in the box of those which show a chemical reaction. dissolving a spoonful of sugar in tea a sparkler burning lava from a volcano cooling freezing orange juice to make an ice lolly car engine burns up petrol mixing ingredients for a cake magnesium ribbon burns leaving white ash water in cloud freezes to form snowflakes logs burning in a fire milk of magnesia cures an upset stomach caused by too much acid produced frying an egg dissolving stock cubes to make soup Glasgow 5-14 Science Programme Education Improvement Service 54