Please find the concentration .

Question

1.Calculate the concentration of a solution made by diluting 30.0 mL of 3.8 M HBr to a final volume of 650.0mL. Use significant figures for final product.

2.What NaCl concentration results when 229mL of a 0.720 M NaCl solution is mixed with 572mL of a 0.420 M NaCl solution?

Answer 1

For the first problem, you can use the formula V1M1 = V2M2

V1 = initial volume

M1 = initial molarity

V2 = final volume

M2 = final molarity

1). (30.0 ml)(3.8 M) = (650.0 ml)(x M)

x = 0.18 M (2 sig. figs.)

2). For this problem, we need to find moles of NaCl in each solutions, find the total final volume, and calculate molarity from these values.

229 ml x 1 L/1000 ml x 0.720 mol/L = 0.16488 moles NaCl

572 ml x 1 L/1000 ml x 0.420 mol/L = 0.2402 moles NaCl

Total moles NaCl = 0.4051 moles

Total volume = 0.229 L + 0.572 L = 0.801 L

Final NaCl concentration = 0.4051 moles NaCl / 0.801 L = 0.506 M (3 sig. figs.)