Question

A standard solution contained 0.842 g/L of solute. A student put 0.2mL of standard and 0.8mL water into a test tube. What is the new concentration in mg/mL? answer with 2 to 4 decimal places rounding correctly, without units.

Answer 1

Answer is: new concentration is 0,168 mg/mL.
d(solution) = 0,842 g/L.
V(solution) = 0,2 mL = 0,0002 L.
V(water) = 0,8 mL.
V₁(solution) = V(solution) + V(water).
V₁(solution) = 0,8 mL + 0,2 mL = 1 mL.
m(solution) = 0,0002 L · 0,842 g/L · 1000.
m(solution) = 0,168 mg.
d₁(solution) = m(solution) / V₁(solution).
d₁(solution) = 0,168 mg/mL.