To Apply the Principles of Stoichiometry to a Familiar Reaction and to Review the Use of the Significant Numbers in Calculations

Jada Ramos

4/15/18

P2

Chemistry Lab

Purpose: The purpose of this lab is to apply the principles of stoichiometry to a familiar reaction and to review the use of the significant numbers in calculations.

Prelab Questions:

There are three significant digits in 4.56 g.

(1.56 g Zn)(mol / 65.39 g Zn) = 0.0239 mol Zn

(0.0378 L)(1.50 m HCl / L) = 0.0567 mol HCl

To decant is to pour from one container into another, especially without disturbing the sediment.

Washing, depending upon the substance used to wash, will remove impurities that are soluble in that particular washing substance.

Balanced equation: Zn + 2HCl ⟶ ZnCl2 + H2

0.0239 mol ⬆️ 0.0567 mol ⬆️ ? ?

(0.0567 mol HCl)(½) = 0.0284 mol HCl

(0.0239 mol Zn)(1/1) = 0.0239 mol ZnCl2

Procedures: Part 1

Get your safety goggles.

Get the mass of a dry test tube and put it in the data table.

Add 1.5 g of zinc to the test tube, get the mass, and put it in the data table.

Fill the buret halfway with 2.50 M of HCl. Remove air from buret tip.

Record original buret reading to the nearest 0.1 ml in the data table.

Add 10 or 15 ml of 1.5 M HCl to test tube using the buret. Record the last measurements.

Observe the reaction and record observations.

Put the test tube on rack.

Wash your hands.

Part 2 (next day)

Get safety goggles.

Observe contents in test and record observations.

Pour the liquid into a dry beaker making sure that the zinc stays in the test tube.

Rinse the contents in the test tube three times and pour the liquid into the beaker.

Find the mass of a evaporating dish and watch glass and record the value.

Pour the contents of the beaker into evaporating dish and cover w/ watch glass. Heat the dish with burner to boil away the water. Let cool.

Reweigh evaporating dish and watch glass to determine the mass of the residue.

Heat the test tube and extra zinc until all the water is evaporated.

Cool the test tube.

Measure mass of test tube and zinc and record the data in the table.

Wash hands before leaving laboratory.

Data Table:

Mass of test tube

19.1g

2) Mass of test tube and zinc

20.6g

3) Initial reading of 1.50 M HCl

22.8ml

4) Final reading of 1.50 M HCl

35.8ml

5) Mass of test tube and zinc after decanting

20.02g

6) Mass of evaporating dish and watch