Page 289 - Chemistry eBook

Density
Mole Calculations Percent Error Percent Composition
Concentration
Combined Gas Law
Titration
Heat
m d = V
number of moles =
d = density m = mass
V = volume
given mass gram-formula mass
Challenge Molarity Problem
% error = measured value – accepted value × 100 accepted value
% composition by mass = mass of part × 100 mass of whole
parts per million = mass of solute × 1 000 000
A 2L solution has a molarity of 10. If the solution is diluted to a molarity of 5, what’s
mass of solution
the new volume?
1. Let’s find the number of moles in the first solution: Reffy, Table T (p. 12)
molarity =
moles of solute
liter of solution
10 = X P1V12
X=20 moles
20
5M= V = M V
MA = molarity of H Answer: X=4
AA BB
P = pressure V = volume
P2V2
2. NowTlet’s adjuTst the equation to match the molarity of 5. We will use the number of
= 12
T = temperature
moles that we just figured out in the previous equation. We are trying to find the
volume now (the number of liters in the solution). +
– MB = molarity of OH
VB = volume of base Hf = heat of fusion
Hv = heat of vaporization C = specific heat capacity
∆T = change in temperature
K = kelvin
°C = degree Celsius
Temperature
X
VA = volume of acid q = heat
q = mC∆T q = mHf
q = mHv
K = °C + 273
m = mass
UNIT 7: SOLUTIONS / SOLUBILITY © 288