A liquid has a molecular weight of 105.141g/mol. Its density is 1.173g/mL. What is the molarity of the pure liquid?

Question

Natalie Anton · Accepted Answer

#"11.16 M"#

Here, your plan will be to take a sample of this compound and determine its mole concentration in milliliters.

If you calculate how many moles of a solute you would get per liter of pure liquid, you can apply the definition of molarity, which is typically defined as moles of solute per liters of solution, to pure liquids as well.

As you know, a substance's molar mass tells you the mass of one mole of that substance. In this case, the liquid is said to have a molar mass of #"105.141 g/mol"#, which means that one mole will have a mass of #"105.141 g"#.

To make the calculations easier, let's pick a #"105.141-g"# sample of this liquid, the equivalent of one mole. You know from the given density that every milliliter of this liquid will have a mass of #"1.173 g"#.

This indicates that the volume that our sample will occupy is

#105.141 color(red)(cancel(color(black)("g"))) * "1 mL"/(1.173color(red)(cancel(color(black)("g")))) = "89.63427 mL"#

Translate this amount into liters.

#89.63427 color(red)(cancel(color(black)("mL"))) * "1 L"/(1000color(red)(cancel(color(black)("mL")))) = "0.08963427 L"#

Lastly, the solution's molarity will be —keep in mind that our sample has precisely one mole of this liquid.

#color(blue)(c = n/V)#

#c = "1 mole"/"0.08963427 L" = color(green)("11.16 M")#

The number of sig figs you have for the liquid's density is the answer, which is rounded to four.

Olivia Anton · Answer

undefined The molarity (M) of the pure liquid can be calculated using the formula:

M = (density * 1000) / molecular weight

Given:
- Molecular weight = 105.141 g/mol
- Density = 1.173 g/mL

Using the formula:

M = (1.173 g/mL * 1000) / 105.141 g/mol

M ≈ 11.15 mol/L