Question

The density of 70.5 wt% aqueous perchloric acid is 1.67 g/mL.
Recall that grams refer to grams of solution (5 g HClO4 1 g H2O).
(a) How many grams of solution are in 1.000 L?
(b) How many grams of HClO4 are in 1.000 L?
(c) How many moles of HClO4 are in 1.000 L?

Answer 1

Answer:

a) Density tells the number of grams/mL, there are 1000 mL in a liter, so

               1.67 g / 1 mL   =   1670 g / 1000 mL = 1670 g/ 1.0 L

b) The formula for percent is

                per cent  =  (part / whole)   x  100

In this case the percent is 70.5, the part is the mass of perchlorate, and the whole is the mass of the solution (1670 g)

Rearranging yields

per cent/ 100   =  mass of perchlorate/ mass of solution

Solving for the mass of perchlorate yields

mass of perchlorate = (percent/ 100)  x mass of solution

So the bottom line is: multiply the grams of solution in 1 L ( 1670 g) by the percentage as a decimal (70.5/100 = .705) to get the mass of perchlorate.

Explanation:

Answer 2

Answer:

The density of 70.5 wt% aqueous perchloric acid is 1.67 g/mL.

Recall that grams refer to grams of solution (5 g HClO4 1 g H2O).

(a) How many grams of solution are in 1.000 L?

(b) How many grams of HClO4 are in 1.000 L?

(c) How many moles of HClO4 are in 1.000 L?

Explanation:

a) Density tells the number of grams/mL, there are 1000 mL in a liter, so

1.67 g / 1 mL   =   1670 g / 1000 mL = 1670 g/ 1.0 L

b) The formula for percent

per cent  =  (part / whole)   x  100

In this case the percent is 70.5, the part is the mass of perchlorate, and the whole is the mass of the solution (1670 g)

Rearranging yields

per cent/ 100   =  mass of perchlorate/ mass of solution

Solving for the mass of perchlorate yields

mass of perchlorate = (percent/ 100)  x mass of solution

So, 1 L ( 1670 g)  (70.5/100 = .705) the mass of perchlorate.