Ocument 10.
A buffer solution is based on methanoic acid, HCOOH (K = 1.70 x 10-4 mol dm3) and
methanoate ions, HCOO-.
I
In the buffer solution, the HCOOH concentration is half the HCOO-concentration.
What is the pH of the buffer solution?
A. 2.47
B. 3.07
C. 3.47
D. 4.07
Your answer
[1]

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a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o