Exam 1
What is the specific heat of some metal if 5266.5 J of heat is required to heat 13.97 grams of that metal 120 °C?
c = 3.142 J/°C g
A balloon contains 0.25 moles of helium gas that occupies 457.2 mL of volume. What is the new volume if the amount of helium gas was increased to 0.45 moles?
V = 822.96 mL or 0.823 L
HI dissociates to form I2 and H2:
2HI(g) → H2(g) + I2(g)
If the concentration of HI changes at a rate of –0.45 M/s, what is the rate of appearance of I2(g)?
Rate of appearance of I2 (g) = 0.225 M/s
The conjugate base and acid of HSO4- is:
Conjugate base: SO4 2-
Conjugate acid: H2SO4
Copper has a specific heat capacity of 0.39 J/°C g. It takes 69.2 J to heat 2.20 grams of copper to 90.0 °C. Knowing this information, what is the initial temperature of copper?
T initial = 9.35°C
What is the molar mass of the unknown gas, if 0.321 gram sample of it occupies 115 mL at 299 K and 1.03 atm?
MM = 66.49 g/mole
Calculate Kc for the decomposition of phosgene at
395 °C, if Kp is 0.0451.
COCl2 (g) = CO (g) + Cl2 (g)
Kc = 0.000823
25.00 mL of 0.10 M HCl is titrated with 0.10 M NaOH. What is the pH at equivalence point?
pH = 7.00
A 110 g block of some metal is heated to 100 °C and then placed in 150 g of water at 24.6 °C. The contents of the calorimeter come to an average temperature of 28.0 °C. What is the specific heat capacity of the metal if the specific heat capacity of water is assumed to be 4.184 J/°C g?
q = 0.269 J/°C g
Find the vapor pressure of a substance at 311 K, if the normal boiling point is at 400 K and the heat of vaporization equals to 29.7 kJ/mol.
Vapor pressure = 58.93 mmHg or 0.078 atm
The half life of isotope X is 2 years.
How many years would it take for a 4 mg sample of X to decay and have only 0.50 mg of it remain?
Time = 6 years
Calculate ∆G˚ and ∆E˚cell using the half-cell reactions below:
Cu 2+ (aq) + 2e- = Cu (s) ∆E˚ = +0.34 V
Pb 2+ (aq) + 2e- = Pb (s) ∆E˚ = -0.13 V
∆E˚cell = + 0.47 V
∆G˚ = - 90.710 kJ/mol or - 90710 J/mol
Given the data below, calculate the enthalpy of the reaction (in kJ).
Ca(OH)2 + 2 H3AsO4 = Ca(H2AsO4)2 + 2 H2O
If:
H of Ca(OH)2 = -986.6 kJ/mol
H of H3AsO4 = -900.4 kJ/mol
H of Ca(H2AsO4)2 = -2346.0 kJ/mol
H of H2O = -285.9 kJ/mol
Enthalpy of the reaction = -130.4 kJ
If you use 3.68 moles of sucrose (C12H22O12) and dissolve this into 2.50 kg of water, what will be the change in the freezing point of your solution.
Assume the Kf of water is -1.86°C/m.
The change in freezing point = 2.74°C
The initial rate data for the reaction
2N2O5(g) → 4NO2(g) + O2(g)
is shown in the following table. Determine the value of the rate constant for this reaction (include units).
Experiment [N2O5](M) Rate (M/s)
1 1.28 × 10^2 22.5
2 2.56 x 10^2 45.0
k = 0.176 1/s
What is the pH of a buffer solution mixed with 200.0 mL of 0.29 M HClO and 100.0 mL of 0.19 M NaClO? The Ka for HClO is 2.9x10^-8.
pH = 7.06
What is the amount of heat required to condense 10 g of steam from 107°C to 50°C?
c of steam = 2.000 J/°C g
c of water = 4.184 J/°C g
H of vaporization = 40.7 kJ/mole
A mix of He and Ne.
There are 5.0 g of He and 5.0 g of Ne. The total pressure of the mix is 2.0 atm. What is the partial pressure of Ne?
Partial pressure of Ne = 1.29 atm
Determine the value of the missing equilibrium constant :
H2 (g) + Br2 (g) = 2 HBr (g) Kc = 3.8x10^4
4 HBr (g) = 2 H2 (g) + 2 Br2 (g) Kc = ?
Kc = 6.925x10^-10
Consider the titration of a 50.0 mL sample of 0.60 M HF with 0.30 M NaOH.
Ka for HF is 6.6x10^-4.
What is the pH after adding 125.00 mL of NaOH?
pH = 12.63