required practical 3: investigation of how the rate of reaction changes with temperature

Question 1

describe the example of the reaction between sodium thiosulfate and hydrochloric acid

Answer 1

1. measure out fixed volumes of sodium thiosulfate and hydrochloric acid using a measuring cylinder
2. use a water bath to gently heat both solutions to the desired temperature before you mix them
3. mix the solutions in a conical flask. place the flask over a black cross which can be seen through the solution. watch the black cross disappear thhrough the cloudy sulfur and time how long it takes to go
4. repeat reaction for solutions at different temperatures. the depth of liquid and the concentrations of the solutions must be kept the same each time

Question 2

describe the results for a higher temperature

Answer 2

-the higher the temperature, the faster the reaction rate and therefore the less time it takes for the mark to disappear

Question 3

describe a way to measure the volume of a gas

Answer 3

1. using a gas syringe to measure the volume of gas being produced
   -you can use this method when one or more of the products is a gas
   -gas syringes give volumes to the nearest 0.1 cm3 so the method is ACCURATE

Question 4

describe a method to measure the decrease in mass

Answer 4

1. when one or more of the products is a gas, you can measure the rate of formation using a mass balance
2. as gas is given off the mass of the reaction mixture decreases
3. this method is accurate and easy, but it releases gas into the atmosphere so usually done in a fume cupboard