Chemistry Final test questions and answers.

Chemistry Final test
questions and answers
What volume of 0.416 M Mg(NO3)2 should be added to 255 mL of
0.102 M KNO3 to produce a solution with a concentration of 0.278 M
NO3- ions? Design an algebra equation.
(x L of .416 M Mg(NO3)2) + (255mL x .102 M KNO3) = (.278 M NO3 *
x)
1. Get all the M converted to what we care about - NO3:
(x Liters of .832 M NO3) + (255mL x .102 M NO3) = (.278 M NO3 * (x
+ 255) )
2. Begin the math:
.832x + .02601 = .278x + .07089
.554x = .04488
x = .08101 L
81 mL of .416 M Mg(NO3)2
Determine how many grams of each of the following solutes would
be needed to make 250 mL of a 0.100 M solution:
(a) cesium iodide (CsI)
(b) sulfuric acid (H2SO4)
(c) sodium carbonate (Na2CO3)
(d) potassium dichromate (K2Cr2O7)
(e) potassium permanganate (KMnO4).
a) .250 L *.1 mol CsI * 259.81 g CsI = 6.4952 grams
1 L 1 mol CsI
b) .250 L *.1 mol CsI * 97.968 g H2SO4 = 2.4492
1 L 1 mol CsI
c) .250 L *.1 mol CsI * 105.965 g Na2CO3 = 2.6491

, 1 L 1 mol CsI
d) .250 L *.1 mol CsI * 293.774 g K2CrO7 = 7.3443
1 L 1 mol CsI
e) .250 L *.1 mol CsI * 157.881 g KMnO4 = 3.947
1 L 1 mol CsI
What is the relationship between two gasses pressure & volume?
P1 x V1 = P2 x V2
What is the ideal gas law equation?
PV=nRT
Pressure x Volume = moles x R constant (.082) x Temperature
What is the conversion of mmHg to atmospheres?
1 atmosphere = 760 mmHg
760 mmHg = 1 atmosphere
760 mmHg/1atm
1 atm/760 mmHg
What is standard temperature & pressure?
273 k, 1 atm, 0 C
What is the formula for percent yield?
actual yield/theoretical yield x 100
What is the approach for balancing an equation?
1. Write out the count of each element
2. Start balancing 1 coefficient at a time, saving O & H for last
3. Focus first on polyatomic atoms & balance, then balance single
element/diatomic molecules (SF4 then F2)
4. Balance O & H
What is the equation for rate of effusion?
What's it called?
1/sqr(MM)
Graham's Law
What is the formulaic definition of pressure?
force/area