Required Practical 10

Question 1

What reaction is this?

Answer 1

Neutralisation of hydrochloride acid and alkali sodium hydroxide

Question 2

What is the independent variable?

Answer 2

Volume of sodium hydroxide

Question 3

What is the dependent variable

Answer 3

Maximum temperature reached

Question 4

What are the controlled variable

Answer 4

Volume of hydrochloric acid
Concentration of hydrochloric acid
Concentration of the sodium hydroxide suction

Question 5

What is the method (14 steps)

Answer 5

1. place 30cm3 of dilute hydrochloric acid into a measuring cylinder
2. transfer the acid into a polystyrene cup
3. place the polystyrene cup into a beaker
   - >which stops the cup falling over
4. use a thermometer to measure the temperature of the hydrochloric acid and record result into a table
5. use a measuring cylinder to measure 5cm3 of sodium hydroxide solution, then transfer it to the polystyrene cup
6. fit a plastic lid onto the cup and place a thermometer into the hole of the lid
7. use the thermometer to gently sir the solution
   - .the temperature will increase
8. read the temperature increase
   - when the temperature stops increasing we record the highest temperature reached
9. rise and dry out the polystyrene cup and start the exterminate all over again
10. repeat this exterminate but this time use 10cm3 of sodium hydroxide solution
11. carry the exterminate serval more times
    - each time increase the volume by 5cm3 each time till we reach 40cm3 of sodium hydroxide solution
12. repeat this exterminate 1 more time so that we have 2 sets of results
    13.use recorded results to calculate a mean value
    for the maximum temperature reached for each volume of sodium hydroxide solution
    14.plot a graph of our results

Question 6

What happens as we increase the volume

Answer 6

As the volume of sodium hydroxide solution is increased then the maximum temperature reached increases

• Because as we add more particles of sodium hydroxide they react with the hydrochloride acid
• Because its exothermic more energy is realised meaning the maximum temperature released increases

Question 7

What happens at a certain volume of sodium hydroxide solution

Answer 7

The maximum temperature reached starts to decrease

• Because we have added so much sodium hydroxide solution that there isn’t enough hydrochloric acid to react it with
• This the amount of energy released has reached a maximum

Question 8

Why does the maximum temperature decrease from the plateaued point

Answer 8

The energy realised is more spread out within a greater volume

Question 9

Why do we use a polystyrene cup with a lid?

Answer 9

The polystyrene cup is a good thermal insulator

• The cup prevents heat from escaping out the sides and the bottom
• The lid prevents heat from escaping out into the air