Calculations
Convert 0.0067 g/mL to kg/L
0.0067 kg/L
What is the molelcular shape of H2O, and what is the bond angle?
Bent, 104.5°
What kind of reaction is always redox?
Single replacement
Is energy absorbed or released when a bond is broken?
Absorbed - energy is required to break a bond
How much (mL) of a 12.0 M HCl solution do you need to make 250 mL of a 1.0 M HCl solution?
20.8 mL
How many Mg atoms are in 2.34 grams of Mg?
5.79 x 1022 atoms
What speed does electromagnetic radiation travel at? (The speed of light)
3.00 × 108 m/s
Write the equation for a reaction between KOH and MgCl2. What kind of reaction is it?
*include states of matter
2 KOH(aq) + MgCl2 (aq) → 2 KCl(aq) + Mg(OH)2 (s)
Double Replacement
What is Hess's Law?
Enthalpy is independent of the reaction pathway. If you can find a combination of chemical equations that add up to the desired overall equation, you can also add up the ΔH's for the individual reactions to get the overall ΔHrxn
If 92.0 grams of Ag2O decompose, how many moles of O2 are produced?
2 Ag2O → 4 Ag + O2
0.198 mol O2
Find the empirical formula of a 100 g sample of a compound that is decomposed into 10 g of C, 0.83 g of H, and 89.07 g of Cl.
CHCl3
How do you find the ΔHrxn? (Heat of reaction)
∑ ΔHf(products) - ∑ ΔHf(reactants)
Heat of formation values of products and reactants
What is Coulomb's Law?
Attraction between particles increases with greater charge and shorter distance.
What is calorimetry?
The process of measuring hear based on observing the temperature change when a body absorbs or discharges energy as heat.
Find the ΔHrxn for 2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(s)
Fe2O3 (s) - ΔHf = -826 kJ/mol
Al2O3 (s) - ΔHf = -1676 kJ/mol
-850 kJ/mol
If 3.00 mL of 0.060 M CuSO4 is diluted to 10.0 mL with water, what is the new molarity of the solution?
What are the intermolecular forces in order of weakest to strongest?
Dispersion, dipole-dipole, hydrogen, ion-dipole
What is Zeff and how do you find it?
Zeff is the effective nuclear charge. The positive charge of an atom's nucleus is reduced by the core electrons.
Zeff = Protons - Core Electrons
When doing a calculation with Hess's Law, does reversing a chemical equation impact the ΔHrxn?
Yes, the sign of ΔHrxn is also reversed.
When 4.50g of NH4Cl is dissolved in 53.00g of water, the temperature of the solution decreases from 20.40 °C to 15.20 °C. How many kJ of heat were released from the water?
1227 kJ
What volume of 0.125 M HNO3, in mL, is needed to react completely with 1.30 g of Ba(OH)2?
2 HNO + Ba(OH)2 → Ba(NO3)2 + 2 H2O
121 mL HNO3
1. Determine the amount (in mL) of the stock solution needed.
2. Add some water to a 250 mL volumetric flask.
3. Pipet the correct amount of the stock solution.
4. Slowly add to the water and swirl
5. Fill the flask to the 250 mL line.
What is the limiting reactant if 5 moles of Al react with 10 moles of O2? How many moles of the excess reactant are left over?
4 Al + 3 O2 → 2 Al2O3
Al is the limiting reactant. 6.25 moles of O2 will be left over.
How is the energy released by a reaction measured in a bomb calorimeter?
There is a jacket of water with a thermometer surrounding the bomb calorimeter's reaction chamber. Heat is released from the chamber and warms the water, which allows the temperature change to be measured and the quantity of energy released to be determined.
A 1.55 g sample of C3H8 was burned in a bomb calorimeter whose heat capacity is 12.3 kJ/°C. The temperature of the calorimeter increased from 21.36 °C to 27.69 °C.
Find the amount of energy released by the reaction, and the heat of combustion per gram of C3H8.
Energy released: 77.9 kJ
Heat of combustion per gram: 50.3 kJ/g