Question

Citric acid (C6H8O7) is a triprotic acid found naturally in lemon juice, and it is widely used as a flavoring in beverages.

Part 1:

What is the molarity of C6H8O7 in commercially available lemon juice if 16.00 mL of 1.50 M NaOH is required in a titration to neutralize 20.0 mL of the juice?

Part 2:

How many grams of citric acid are in 100.0 mL of the juice?

Answer 1

1)

we have the Balanced chemical equation as:

3 NaOH + H3C6H5O7 ---> Na3C6H5O7 + 3 H2O

Here:

M(NaOH)=1.5 M

V(NaOH)=16.0 mL

V(H3C6H5O7)=20.0 mL

According to balanced reaction:

1*number of mol of NaOH =3*number of mol of H3C6H5O7

1*M(NaOH)*V(NaOH) =3*M(H3C6H5O7)*V(H3C6H5O7)

1*1.5*16.0 = 3*M(H3C6H5O7)*20.0

M(H3C6H5O7) = 0.400 M

Answer: 0.400 M

2)

volume , V = 100 mL

= 0.1 L

we have below equation to be used:

number of mol,

n = Molarity * Volume

= 0.4*0.1

= 4*10^-2 mol

Molar mass of C6H8O7 = 6*MM(C) + 8*MM(H) + 7*MM(O)

= 6*12.01 + 8*1.008 + 7*16.0

= 192.124 g/mol

we have below equation to be used:

mass of C6H8O7,

m = number of mol * molar mass

= 4*10^-2 mol * 192.124 g/mol

= 7.68 g

Answer: 7.68 g