experiment enthalpy change

Chemistry Experiment TheEnthalpy Change in Neutralization Name:

1.AIM

To calculate the enthalpy change in the reactions between acids and alkalis (neutralization reaction).

To be more understanding about enthalpy, acidic solution and basic solution.

2.PRINCIPLE

Formula: Q= H=qcm

Equation: NaOH(aq)+HCl(aq) H2O(l)

Key concepts: We could use a thermometer and the heat preserving equipment to calculate the change of heat about the reaction. Then we can use the change of heat and the number of mole to calculate the enthalpy change.

3.CHEMICALS&EQUIPMENTS

（1）HCl solution (25ml 1mol/L) （2）NaOH powder (1g)

（3）Enough distilled water (H2O) （4）Different size of beakers

（5）Rubber dropper （6）Glass stick

（7）spoon (8)cylinder

(9)thermometer (10)stuff to fill the crack between two beaker (11)electronic scale

4.PROCEDURES

[1] Put a clean beaker on a electronic scale and zeroed the electronic scale. Then, use spoon and electronic scale to measure out 1g NaOH powder.

[2] Pour 39g water into the beaker and dissolve the NaOH powder with a glass stick.

[3] Then, use the cylinder and the rubber dropper to measure out 25ml HCl solution.

[4] When the two solutionsare cooled to the same temperature, use the thermometer to measure the temperature of the two solutions and record down. [5] Then put one of the small beaker which has one of the two solutions in it, into a bigger beaker and use the stuff to fill the crack between them.

[6] Pour the other lind of solution into it and use glass stick to help it reacts and observing thermometer which insert to the solution until the temperature goes up and down. Record down the highest temperature.

[7]Use the formula Q= H=qcm to calculate the enthalpy change (the heat capacity of water is 4.18J/gK).

5.ATTENTION

{1}Remember to clean the beakers before and after using them with distilled water. {2}Be careful not to pour the NaOH solution into the beaker with HCl solution until it was cooled down to the same temperature with HCl solution.

{3}Attentions do not measure the NaOH the on paper, because NaOH can react with CO2and can absorb water, which will stick the chemicals on the paper and have more error.

{4}Make sure that you really get the highest temperature of the solution.

6.MEASUREMENT

7.ERROR

[1]Lost some heat out of the water in to the beaker or the stuff between the beakers.

[2]There may not be so much number of mole of HCl and NaOH reacted since the NaOH may react with the CO2in the air and the HCl also may volatilized to the air already.

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