Question

8. Calculate the following. a. Molarity of solution made by dissolving 35.00 grams of NaC,H,O2 in 1.25 L solution b. Number of moles in 25.0 mL of 0.00150 M BaCl2 c. Grams of HNO3 in 250.0 mL of 14.3 M HNO3 d. Milliliters of 0.750 M H3PO4 that contain 0.150 mol H3PO4 e. Milliliters of 0.825 M H2SO4 that contain 7.82 x 10" molecules of H2SO4 9. Forensic chemists use Super Glue to help them see fingerprints left behind at crime scenes. If cyanoacrylate, the main component of Super Glue®, is vaporized, it will be attracted to the oils left behind after someone touches an object. Forensic investigators will then rinse the print with a solution of europium chloride hexahydrate, EuCl 6 H:0, which fluoresces when exposed to ultraviolet light. If 0.625 g of europium chloride hexahydrate is dissolved in enough water to make 500.0 mL of solution, what is the molarity of the solution?

Answer 1

8)

a)

Molar mass of NaC2H3O2,

MM = 1*MM(Na) + 2*MM(C) + 3*MM(H) + 2*MM(O)

= 1*22.99 + 2*12.01 + 3*1.008 + 2*16.0

= 82.034 g/mol

mass(NaC2H3O2)= 35.00 g

use:

number of mol of NaC2H3O2,

n = mass of NaC2H3O2/molar mass of NaC2H3O2

=(35 g)/(82.03 g/mol)

= 0.4267 mol

volume , V = 1.25 L

use:

Molarity,

M = number of mol / volume in L

= 0.4267/1.25

= 0.3413 M

Answer: 0.341 M

b)

volume , V = 25 mL

= 2.5*10^-2 L

use:

number of mol,

n = Molarity * Volume

= 1.5*10^-3*2.5*10^-2

= 3.75*10^-5 mol

Answer: 3.75*10^-5 mol

c)

volume , V = 2.5*10^2 mL

= 0.25 L

use:

number of mol,

n = Molarity * Volume

= 14.3*0.25

= 3.575 mol

Molar mass of HNO3,

MM = 1*MM(H) + 1*MM(N) + 3*MM(O)

= 1*1.008 + 1*14.01 + 3*16.0

= 63.018 g/mol

use:

mass of HNO3,

m = number of mol * molar mass

= 3.575 mol * 63.02 g/mol

= 2.253*10^2 g

Answer: 2.25*10^2 g

d)

use:

M = number of mol / volume in L

0.75 = 0.15/ volume in L

volume = 0.2 L

volume = 2*10^2 mL

Answer: 200 mL

Only 4 parts at a time please