endo/exothermic reactions + (Required Practical)

Question 1

what is the independent variable in this experiment

Answer 1

the colume of sodium hydroxide solution

Question 2

what is the control variable

Answer 2

the volume of hydrocloric acid and the concentration of both the hydrochloric acid and the sodium hydroxide solution

Question 2

what is the dependent variable in this experiment

Answer 2

the maximum temperature reached

Question 3

how can we figure out the temperature change in an exothermic reaction

Answer 3

1. use a measuring cylinder to measure 30cm3 of dilute hydrochloric acid.
2. transfer the acid into the polystyrene cup
3. put the polystyrene cup inside a beaker this will stop the cup from falling over
4. use a thermometer to measure the temperature of the acid record this in a table
5. measure 5cm3 of sodium hydroxide in a measuring cylinder and transfer this into the polystyrene cup
6. fit a plastic lid to the cup and place a thermometer in the hole and make sure the bulb is in the solution
7. use the thermometer to stir the solution
8. now look at the temperature rise of the solution
9. when the reading on the thermometer stops increasing then record the highest temperature reached
10. rinse out and dry the polystyrene cup
11. now repeat the hole experiment with 10cm cubed of sodium hydroxide solution
12. do this experiment a couple more times increasing the volume of sodium hydroxide solution by 5cm cubed until you reach 40cm cubed of sodium hydroxide solution

13 repeat the whole experiment one more time to get 2 sets of results

Question 4

what happens to the temperature when more volume of sodium hydroxide was added

Answer 4

the maximum temperatures reached increased each time this is because there was more sodium hydroxide to react with hydrochloric acid

Question 5

what will happen to the temperature in the solution and why would it happen

Answer 5

because the reaction is exothermic and would increase the temperature

Question 6

what happens when you add too much sodium hydroxide solution

Answer 6

the maximum temperature reached decreases because there is not enough hydrochloric acid to react with.

Question 7

why do you use a polystyrene cup and a lid in this experiment

Answer 7

to reduce the amount of heat loss and that polystyrene is a good insulator