1) You are asked to make 171 mL of 1.022 M HCl starting with 9.0 M HCl. 2) You s

Question

1) You are asked to make 171 mL of 1.022 M HCl starting with 9.0 M HCl.

2) You standardize the "1.022 M" HCl by pipetting a known amount of it into a flask and titrating to the phenolphthalein endpoint with an NaOH solution of known concentration
Experimental Data:

Calculate:

3) You weigh an empty gas buret, fill it to the 50.00 mL mark with distilled water and weigh it again.
Experimental Data:

Calculate:

4) You pipet a known amount of this standardized HCl into a 15 cm sample tube and float a "boat" containing your unknown.
You hook up the sample tube and contents to the gas buret.
You shake the tube to sink the boat and to start the reaction.
When the metal unknown is completely dissolved, you read the gas buret and measure the height of the buret's meniscus above the water level.
Experimental Data:

Calculate (R = 0.0821 L atm/mol K):

5) The remaining solution in the 15 cm sample tube containing the reaction products and the unused HCl is quantitatively transfered to a flask and titrated to its endpoint with the standard NaOH.
Experimental data:

Calculate:

a) The volume of 9.0 M HCl needed is (to 0.1 mL) ______________ mL

Explanation / Answer

1)

a) Use M1V1=M2V2

V1=(1.022 M x 171 mL)/ 9.0 M= 19.418 mL

The volume of 9.0 M HCl needed is (to 0.1 mL)= 19.418 mL

2)

MV HCl=MVNaOH

MHCl= (MVNaOH)/V HCl

MHCl=(0.1892 x 22.74)/ 4.27= 1.0075 M

b) Exact molarity of your HCl ___1.0075___________ M

3)

c) Density of water at 27.6 °C (by interpolation) _______0.99615_______ g/cc

d) Volume of water filling buret to 50.00 mL mark ____53.77__________ mL e) Extra volume of water in addition to the 50.00 mL ______3.77________ mL

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