Investigating Temperature Change when Different Volumes of Acid and Alkali are Mixed

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Investigating Temperature Change when Different Volumes of Acid and Alkali are Mixed

Prediction

==========

My prediction is that the biggest temperature change will be when

there are equal amounts of H+ ions and OH-, this is because create an

optimum mixture for the ions to neutralise each other.

Apparatus

=========

v Empty plastic yoghurt cup

v thermometer

v Hydrochloric Acid

v Sodium Hydroxide

v Two measuring cylinders

[IMAGE]

Diagram

=======

[IMAGE]

[IMAGE] 30ml³ Hydrochloric acid

[IMAGE]

[IMAGE]Thermometer

[IMAGE][IMAGE] Measuring Cylinder

[IMAGE] Plastic cup

[IMAGE]

[IMAGE]

30ml³ Sodium

Hydroxide

Method

======

First of all we decided to use a plastic cup because it was easy to

wash off the mixture. We poured out 30ml of Hydrochloric acid in to

one measuring cylinder and poured 30ml of Sodium Hydroxide into the

other measuring cylinder. Then we added the Sodium Hydroxide to the

plastic cup and left it for 25-30 seconds, we then took the

temperature of the alkali before adding the acid. We then tipped the

Hydrochloric acid into the cup with the alkali. We stirred the cup for

25-30 seconds and then recorded the new temperature, and then we

washed out the mixture before doing the next experiment. We then tried

out different combinations- 40:20, 20:40, 15:45 and 45:15. Just to

make sure we had reliable results we carried out the experiment twice

and took an average from the two results.

Results Table

=============

1st Results

Chemicals + Measurements

Temperature

[IMAGE]30ml³ of Sodium Hydroxide

+

30ml³ of Hydrochloric Acid

Start

20ºC

End

26ºC

Rise

6ºC

[IMAGE]40ml³ of Sodium Hydroxide

+

20ml³ of Hydrochloric Acid

Start

20ºC

End

27ºC

Rise

7ºC

[IMAGE]20ml³ of Sodium Hydroxide

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