Chemists often use molarity M , in moles/liter , to measure the concentration of

Question

Chemists often use molarity M , in moles/liter , to measure the concentration of solutions. Molarity is a common unit of concentration because the volume of a liquid is very easy to measure. However, the drawback of using molarity is that volume is a temperature-dependent quantity. As temperature changes, density changes, which affects volume. Volume markings for most laboratory glassware are calibrated for room temperature, about 20?C .

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What I tried for Part A, which is wrong:

1 L (.0235mol/L) = .0235

999.4 mL x (.9982 g/mL) = 997.601 g H2O

(.0235/997.601) x 1000 = .023556 which is wrong!

Please provide the correct answers for parts A - D with detailed explanation

Explanation / Answer

Dear , Please provide weight of the salt and how much quantity of solution required.

For eg, if we consider NaCl is a salt and soluble in one litre of water, take 58.44 gms of NaCl in 1000 ml water. Hence the molality of NaCl = no.of moles of NaCl/ weight of water = 58.44/58.44/1Kg = 1.000 mol/Kg.

Molefraction of salt = amount (mol) of salt / (amount (mol) of salt + amount (mol) of water)

=1/(1+55.55) = 0.018

where amount (mol) of salt = weight of salt/molar mass of salt = 58.44/58.44 = 1.000

amount (mol) of solvent = weight of water/ molar mass of water = 1000/18 = 55.55

Concentration ogf the salt in percentage by mass =( weight of salt / weight of salt solution) X 100

= (58.44/ (58.44+1000) ) X 100 = 5.521 W/W %

Concentration of salt solution in parts per million = 58440 parts per million

one parts per million = 1mg/liter

the amount of salt in mg = 58440 mg

Hence the concenrtation of salt solution = 584.4 x 102 parts per million

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