H2O = A universal solvent
- Solutions are homogeneous(composed of similar or identical parts or elements) mixtures
- Homogeneous mixtures are composed of a SOLUTE and a SOLVENT
- A Solute is the chemical present in lesser amount (dissolved)
- A Solvent is the chemical present in the greater amount (whatever does the dissolving)
- CHEMICALS DISSOLVED IN WATER ARE AQUEOUS! ie. H2SO4(aq) ---> dissolved in H2o. How much? This is the CONCENTRATION
Basically, molarity is MOLES/ VOLUME
MOL/L = M (MOLARITY)
Getting it? Good.
Examples:
DETERMINE THE CONCENTRATIONS OF THE SOLUTIONS BELOW:
a) 0.118 mol of water in 2.50 L
0.118 mol
2.50 L
= 4.7 x 10^-2 M or mol/L
b) 12.5 g of PbCl2 in 30 mL of water
*First change grams into moles, than change mL into L, than take your moles and divide by your amount of liters!
12.5 g x 1 mol = 0.0448 mol
278.2 g
30 mL x 1 L = .03 L
1000mL
SOLUTION: 0.0448 mol
.03 L
= 1.49 M
= 1.5 M
Now lets crank up the chemistry and do so more difficult questions!
How many litres of solution are required to make the following solutions?
a) 0.250 mol dissolved to create a 1.75 M solution of Na2S
0.25 mol x 1 L = 0.143 L
1.75 mol
*for these types of equations, you can flip mol/L to become L/mol since you're trying to find L!
b) 35.0 g of I2 used to create a 0.150 M solution
35.0 g x 1mol = .138 mol x 1L = .919 L
253.8g 0.150 M
Pretty easy stuff no?? HERE IS A VIDEO TO HELP EXPLAIN TO YOU THE CONCEPT OF MOLARITY IF YOU'RE HAVING SOME TROUBLE! Go around the 4 minute mark because the guy sneezes haha...LOL!
Post by Ren Flores
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