This if for the chem lab practical I take on Tuesday night! If you could answer

Question

This if for the chem lab practical I take on Tuesday night! If you could answer them and show your work that'd be great so I know exactly how to do them and can do well on the actual test! Thank you!

Chemistry 211   Lab Final Study Guide   Spring 2015

Useful Information:
1 ampere =coulomb/sec
Faraday’s constant = 96,500 coulombs/mole of electrons
Molar mass of Au = 197.0 g/mole, Molar mass of Cu = 63.55 g/mole
m = moles ,   '   ’

c   kg

Tf

= Tf

Tf

where Tf is for the pure solvent and Tf

is for the mixture.

T = (K

)(m ) ,

m = (

(mass of

solute, g )
)(   ).

f   f   c

c   molar

mass, g

mol 1

mass of

solvent, kg

4.   Next question
(a)   What is the pH of 0.1M HCl? Show your work. (5pts)

(b)   Which of the following results in the smallest change in pH? Circle your answer.

(i)   Add 1mL of 1M HCl to 100mL of water.

(ii)   Add 1mL of 1M HCl to 100mL of a buffer.

(iii)   Add 1mL of 1M HCl to 10 mL of water.

5.   Next question
(a)   CH3COOH + OH- CH3COO- + H2O
If you titrate a solution containing 0.385 moles of acetic acid, how many moles of NaOH will you need to reach the equivalent point?

(b)   In which solution is PbF2 the most soluble? Circle your answer. (5pts)

(i)   pure H2O

(ii)   0.1M PbCl2

(iii)   0.1M NaF

6.   Au3+ + 3e- Au (s)
(a)   If 12 moles of electrons are provided to a solution containing an excess of Au3+, how many moles of Au(s) will form? (5pts)

(b)   How long (in hours) must you perform electrolysis with a current of 1.06 amperes to obtain enough gold to make a ring that weighs 9.82 grams?

Explanation / Answer

4) a) 0.1 M HCl: [H+] = 0.1

pH = -log(H+) = -log(0.1) = 1

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