Question

Return Submit 5 points What is the molality of a solution of 20.% of a compound with a molar mass of molar mass=208.46 g/mol by mass? The density of the solution is 1.18 g/ml BIVAAI EE XX, e 12p . Paragraph - EAD 5 points A solution is 0.125 Min HNO, and 0.225 M in NaNO2. The K, for HNO2 is 4.5' 104. What is the pH of 100.0 mL of this solution after 1.00 mL of 3.00 M NaOH is added? BI y A -A- IE 3 XX , 12pt - Paragraph - E 1

Answer 1

1)                
                      
                                        Molality = Mole of Solute / Kg of Solvent

20% solution of a compound means
20 gram of compound in 100 gram of solution

So, no of grams of solvent is 100 - 20 = 80 grams of solvent

Now we have to convert the grams of the compound to Moles.

Molar mass is given as 208.46 g / mole which means 1 mole of the compound weighs 208.46 grams.

we have to find the number of moles in 20 grams of compound.

1 mole = 208.46 g

1 g = 1 / 208.46

20 g = 20 / 208.46 moles

20 g = 0.0959 moles

we know that 1 kg = 1000 grams then 80 grams is 0.080kg

So,

Molality = 0.0959/ 0.080

                                                             Molality = 1.19875 mol / kg