Question

Isopropanol (C3H8O) is a key ingredient in some hand sanitizers. Suppose that 127 grams of isopropanol is dissolved in water. The volume of the solution is 1,250 milliliters. What is the molarity of the solution? Refer to the periodic table to help you answer. Express your answer to three significant figures. The molarity of the solution is M.

Answer 1

Answer: 1.69 M

Step-by-step explanation:

1) Data:

a) mass of solute: 127 g

b) volume of solute: 1,250 ml = 1.25 liters

c) compound: C₃H₈O

d) M = ?

2) Formulae:

a) M = number of moles of solute / volume of solution in liters

b) number of moles = mass in grams / molar mass

3) Solution

a) molar mass of C₃H₈O:

element number of atoms atomic mass mass of the element

a.m.u. g / mol

C 3 12.011 3 × 12.011 = 36.033

H 8 1.008 8 × 1.008 = 8.064

O 1 15.999 15.999

---------------------------------

Sum = molar mass = 60.096 g/mol

b) number of moles = mass in grams / molar mass = 127 g / 60.096 g/mol = 2.113 mol

c) M = number of moles of solute / volume of solution in liters = 2.113 mol / 1.250 liter = 1.69 M (showing 3 significant figures).

Answer 2

Answer:- 1.69M

Solution:- Molarity is moles of solute per liter of solution. We have 127 grams of the solute, isopropanol and the volume of the solution is 1250 mL. We need to convert the grams to moles and the mL to L.

Molar mass of
`C_3H_8O` = 3(12.011) + 8(1.008) + 1(15.999) = 60.096 gram per mol

Let's convert the grams to moles as:

`127gC_3H_8O((1mol)/(60.096g))`

= 2.11 mol

The volume is 1250 mL that is 1.25 L.

`molarity=(2.11mol)/(1.25L)`

= 1.69M

So, the molarity of the solution is 1.69M.