Question

1) What is the concentration of KHP, in molarity, when 5.951 g of KHP is dissolved in 58 mL of water? Report your answer to two (2) decimal places in molarity.

2) How many mL of a 1.37 M sodium hydroxide solution are required to react completely with 195 mL of a 0.57 M hydrochloric acid solution? Report your answer to the nearest mL.

Answer 1

1)
KHP is C8H5KO4

Molar mass of C8H5KO4,
MM = 8*MM(C) + 5*MM(H) + 1*MM(K) + 4*MM(O)
= 8*12.01 + 5*1.008 + 1*39.1 + 4*16.0
= 204.22 g/mol


mass(C8H5KO4)= 5.951 g

use:
number of mol of C8H5KO4,
n = mass of C8H5KO4/molar mass of C8H5KO4
=(5.951 g)/(2.042*10^2 g/mol)
= 2.914*10^-2 mol
volume , V = 58 mL
= 5.8*10^-2 L


use:
Molarity,
M = number of mol / volume in L
= 2.914*10^-2/5.8*10^-2
= 0.5024 M
Answer: 0.50 M

2)
Balanced chemical equation is:
HCl + NaOH ---> NaCl + H2O


Here:
M(HCl)=0.57 M
M(NaOH)=1.37 M
V(HCl)=195.0 mL

According to balanced reaction:
1*number of mol of HCl =1*number of mol of NaOH
1*M(HCl)*V(HCl) =1*M(NaOH)*V(NaOH)
1*0.57 M *195.0 mL = 1*1.37M *V(NaOH)
V(NaOH) = 81.1314 mL

Answer: 81 mL