Question

Automobile battery acid is 38% H2SO4 and has a destiny of 1.29g/ml. Calculate the molality and the molarity of this solution. ​

Answer 1

Answer:

$M=5.0M\\\\m=6.2m$

Explanation:

Hello,

In this case, 38 % is commonly a by mass concentration, meaning that we have 38 grams of solute (sulfuric acid) per 100 grams of solution (water+sulfuric acid):

$38\%=\frac{m_{H_2SO_4}}{m_{H_2SO_4}+m_{H_2O}}$

Hence, we compute the moles of sulfuric acid in 38 grams by using its molar mass (98 g/mol):

$n_{H_2SO_4}=38g*\frac{1mol}{98g}=0.39mol H_2SO_4$

Next, the volume of the solution in litres by using the density of the solution:

$V_{solution}=100g*\frac{1mL}{1.29g}*\frac{1L}{1000mL} =0.0775L$

This is done since the molarity is defined as the ratio of the moles of the solute to the volume of the solution in litres, thus we have:

$M=\frac{n}{V}=\frac{0.38mol}{0.0775L}=5.0M$

On the other hand, the molality is defined as the ratio of the moles of the solute to the mass of the solvent in kilograms, thus, we compute the mass of water (solvent) as shown below:

$m_{H_2O}=100g-38g=62g*\frac{1kg}{1000g}=0.062kg$

So compute the molality:

$m=\frac{n_{solute}}{m_{solvent}}=\frac{0.39mol}{0.062kg}=6.2m$

Regards.

Answer 2

Answer:

$Molarity=5.00mol/litre$

$Molarity=6.200mol$

Explanation:

Mass percent of H2SO4 is 38%

destiny of 1.29g/ml

Molecular weight of H2SO4

(1×2) +(32) +(16×4) = 98g-mol.

CHECK THE ATTACHMENT FOR DETAILED EXPLANATION: