2016 hsc help chemistry (1 Viewer)

[cloud edwards]

How does one do Question 18 of 2016 HSC Chemistry

Question: 40 mL of 0.10 mol L–1 NaOH is mixed with 60 mL of 0.10 mol L–1 HCl.
What is the pH of the resulting solution?
(A) 7.0
(B) 1.7
(C) 1.4
(D) 1.2

ANSWER IS: B

Thanks

Paper
https://educationstandards.nsw.edu....-e76232cd-1d84-4d3e-92ce-ea41546810f6-lHPDE.v

Answers
http://educationstandards.nsw.edu.a...-818e942f-37a4-4ee9-a5ec-e40c59e01834-lJl54sm

 

[jazz519]

Write a chemical equation naoh + hcl ---> nacl + h2o

Find moles of the two reactants
n(naoh) =0.004 moles
n(Hcl)=0.006 moles

So hcl is in excess, thus after all the naoh reacts there is still 0.002 moles of hcl remaining

Thus h+ concentration=0.002/0.1=0.02

So ph=-log(0.02)=1.69