Category 1
What is molarity(M)?
amount(mol) of solute/volume (L) of solution
What is molality(m)?
amount(mol) of solute/mass(kg) of solvent
What is Parts by mass?
mass of solute/mass of solution
What is parts by volume?
volume of solute/volume of solution
amount(mol) of solute/amount(mol) of solute+amount(mol) of solvent
Name two factors that influence reaction rate?
Concentration, physical state, temperature
When is the reaction fastest? the beginning or the end?
The beginning because there are more reactants to react with each other
What is the rate for the reaction?
aA + bB -> cC +dD
-1/a d[A]/dt = -1/b d[B]/dt = 1/c d[C]/dt = 1/d d[D]/dt
What is the rate law for the following reaction?
aA + bB -> cC +dD
Rate= k[A]m[B]n
2NO(g) + O2(g) -> 2NO2(g); Rate= k [NO]2[O2]
Determine the reaction order with respect to each reactant and the overall order
Second order with respect to NO, first order with respect to O2 and third order overall
2H2(g) + O2(g) -> 2H2O(g)
A.)Express the rate in terms of changes in [H2], [O2], and [H2O] with time.
B.)When [O2] is decreasing at 0.23 mol/L*s, at what rate is [H2O] increasing?
A.) Rate= -d[O2]/dt = -1/2 d[H2]/dt = 1/2 d[H2O]/dt
fractions are from the coefficients
B.) 0.46 mol/L*s
1/2 d[H2O]/dt = -d[O2]/dt = -(-0.23 mol/L*s)
d[H2O]/dt = 2(0.23 mol/L*s)
Which integrated rate law involves ln?
first order
The decay of dioxygen is observed to be 13.5 M/s, what is the rate of observation of increase of the carbon dioxide in the combustion of pentane?
C5H12 + 8O2 -> 5 CO2 + 6 H2O
8.44 M/s
The following is a first-order reaction and the rate constant is 9.2 s-1. What is the half-life of the reactions? How long does it take for the concentration to reach one-quarter of the initial value?
A.) t1/2 = 0.693/k=0.693/9.2 s-1= 0.075 s
B.) 2(0.075)= 0.15s
What is the half-life equation for second-order reaction?
t1/2= 1/k[A]0
What is the molality of a solution prepared by dissolving 32.0 g of CaCl2 in 271 g of water?
m=moles CaCl2/kg solvent(H2O)=0.288mol CaCl2/0.217 kg H2O=1.06m
Find the concentration of calcium (in ppm) in a 3.50-g pill that contains 40.5 mg of Ca?
(40.5 mg Ca2+ x (1g/103mg))/3.50g=1.16x104 ppm Ca2+
The label on a 0.750-L bottle of Italian chianti indicates "11.5% alcohol by volume." How many liters of alcohol does the wine contain?
0.750 L chianti x 11.5 L alcohol/100. L chianti = 0.0862 L alcohol
A sample of rubbing alcohol contains 142 g of isopropyl alcohol (C3H7OH) and 58.00 g of water. What are the mole fractions of alcohol of alcohol and water?
2.36 mol C3H7OH
3.22 mol H2O
X(C3H7OH)= 0.423
X(H2O)= 0.577
C4H8 decomposes in a first order reaction, with the very high rate constant 87 s-1, to towo molecules of C2H4. If the initial C4H8 is 2.00 M, what is the concentration after 0.01 s?
0.83 mol/L
An aqueous solution of H2O2 is 30.0% by mass and has a density of 1.11 g/mL. What is the molality?
g of H2O=100. g solution- 30.0 g H2O2= 70.0 g H2O
30.0 g H2O2 x 1 mol H2O2/34.02 g =0.882 mol H2O2
molality= 0.882 mol/70.8g x 1kg/103
12.6 m H2O2
An aqueous solution of H2O2 is 30.0% by mass and has a density of 1.11 g/mL. What is the mole fraction H2O2?
0.185
An aqueous solution of H2O2 is 30.0% by mass and has a density of 1.11 g/mL. What is the molarity?
9.79 M H2O2
A higher temperature increases or decreases with k?
Increases
2HI(g)->H2(g) + I2(g) has rate constants of 9.51 x 10-9 M-1s-1 at 500. K and 1.10x10-5M-1s-1 at 600. K. Find the activation energy
ln(k2/k1)= - Ea/R(T2-T1)-1
R=8.314J/mol*K
1.76x105 J/mol