Concentrated HCl has a density of 1.19 g/mL and is 38.0% by mass HCl

mass-water

#1

Concentrated HCl has a density of 1.19 g/mL and is 38.0% by mass HCl (the rest of the mass is water). How many mL of this concentrated solution do you need to add to a 250.0 mL volumetric flask to create a 0.0500 M HCl solution? Give your answer to the hundredths decimal place and do not include any units. The MW of HCl is 36.46 g/mol.

Answer:

Moles of HCl needed= final volume x final concentration
= 250.0/1000 x 0.0500 = 0.0125 mol

Mass of HCl needed = moles x molecular weight
= 0.0125 x 36.46 = 0.45575 g

Mass of concentrated HCl needed = 100/38.0 x 0.45575
= 1.199 g

Volume of concentrated HCl needed = mass/density
= 1.199/1.19
= 1.008 ≈ 1.01 mL

Thus mL of concentrated HCl = 1.01 (rounded to the hundredths decimal place).