Lemon juice normally has a pH of 2 If all the acid in the lemon juice is citric acid and there are no citrate salts present, then what will be the citric acid concentration [HCit] in the lemon juice ? (Assume that only the first hydrogen of citric acid is important) HCit leftharpoons H ++ Cit -, K a =8.4 × 10-4 mol L -1

Question

Lemon juice normally has a pH of 2 If all the acid in the lemon juice is citric acid and there are no citrate salts present, then what will be the citric acid concentration [HCit] in the lemon juice ? (Assume that only the first hydrogen of citric acid is important) HCit leftharpoons H ++ Cit -, K a =8.4 × 10-4 mol L -1 (A) 8.4 × 10-4 M (B) 4.2 × 10-4 M (C) 16.8 × 10-4 M (D) 12.0 × 10-2 M

Tardigrade Admin · Accepted Answer

[ H +]=√K a C, pH =2, ∴ [ H +]=10-2 M 10-2=√K a C 10-4=8.4 × 10-4 × C ∴ C=11.9 × 10-2 m

$8.4 \times 1 0^{- 4} M$

$4.2 \times 1 0^{- 4} M$

$16.8 \times 1 0^{- 4} M$

$12.0 \times 1 0^{- 2} M$

$[H^{+}] = K_{a} C, p H = 2$ ,

$∴ [H^{+}] = 1 0^{- 2} M$

$1 0^{- 2} = K_{a} C$

$1 0^{- 4} = 8.4 \times 1 0^{- 4} \times C$

$∴ C = 11.9 \times 1 0^{- 2} m$

8.4×10−4M

4.2×10−4M

16.8×10−4M

12.0×10−2M

[H+]=Ka​C​,pH=2, ∴[H+]=10−2M 10−2=Ka​C​ 10−4=8.4×10−4×C ∴C=11.9×10−2m

$8.4 \times 1 0^{- 4} M$

$4.2 \times 1 0^{- 4} M$

$16.8 \times 1 0^{- 4} M$

$12.0 \times 1 0^{- 2} M$

$[H^{+}] = K_{a} C, p H = 2$ ,

$∴ [H^{+}] = 1 0^{- 2} M$

$1 0^{- 2} = K_{a} C$

$1 0^{- 4} = 8.4 \times 1 0^{- 4} \times C$

$∴ C = 11.9 \times 1 0^{- 2} m$