Stoichiometry
Solutions
Thermochemistry
Definitions
Equations
100
How many moles are in 98.3 grams of aluminum hydroxide, Al(OH)3?
1.26 moles Al(OH)3
100
Categorize the following as non electrolytes, weak electrolytes, or strong electrolytes: a) H2SO4 b) HF c) CH3OH
a) strong electrolyte b) weak electrolyte c) nonelectrolyte
100
Name 3 state functions
Volume, pressure, temperature, internal energy, enthalpy, etc.
100
Define molarity
Molarity (M): the number of moles of solute per liter of solution: M=moles/liter
100
What is the % yield equation?
(actual / theoretical ) x 100
200
Balance the following equation: ____AgNO3 + _____Ga → _____Ag + _____Ga(NO3)3
3, 1, 3, 1
200
What is the general reaction for Neutralization (acid-base) reactions?
Acid + water = salt + water
200
Identify the following as endothermic or exothermic, and tell whether bonds are being made or broken. 2HgO → 2Hg + O2 ∆H = + 181 kJ
Endothermic! Bonds are being broken
200
Define a net ionic equation
a balanced equation that describes the actual reaction taking place in solution; it is obtained by eliminating the spectator ions from the total ionic equation.
200
What is the dilution equation (include units)
M1V1 = M2V2 M in moles/liter V in liters
300
Find the percent compositions of all of the elements in the following compounds: CuBr2
Cu: 28.4% Br: 71.6% Mass of Cu in the compound x 100 = Percent Composition Total Mass of CuBr2 Compound 63.546 grams x 100 = 28.4% 223.354 grams
300
Complete the following reaction: NaOH(aq) + AgNO3(aq) --> What kind of reaction is this?
Products: NaNO3(aq) + AgOH(s) This is a precipitation run!!
300
1. How much heat is needed to bring 12.0 g of water from 28.3 °C to 43.87 °C, if the specific heat capacity of water is 4.184 J/(g•°C)?
783J ∆T=43.87°C–28.3°C=15.6°C q = mcΔT = (12.0g)(4.184 J/g•°C)(15.6°C) = 783J Heat is absorbed by the system.
300
Define oxidation
a chemical change in which an element loses electrons; the oxidation number of the element increases. THIS IS THE REDUCING AGENT
300
Consider a beaker of pure water and a swimming pool of pure water. Which of the following statements are true about the water in each case? 1. They have the same heat capacity 2. They have the same molar heat capacity 3. They have the same specific heat capacity.
2 and 3!
400
What is the empirical formula for a compound which contains 0.0134g iron, 0.00769g of sulfur, and 0.0115g of Oxygen?
FeSO3
400
What is the ionic and net ionic equation of the following molecular equation: Na2CO3(aq) + FeCl2(aq) --> FeCO3(s) + 2NaCl(aq)
Ionic:2Na+(aq) + CO32-(aq) + Fe2+(aq) + 2Cl-(aq) --> FeCO3(s) + 2Na+(aq) + 2Cl-(aq) Net Ionic: CO32-(aq) + Fe2+(aq) --> FeCO3(s)
400
How much energy is absorbed or released (identify which) when each of the following reactions takes place? CH4 (g) + Cl2 (g) --> CH3Cl (g) + HCl (g) The relevant bond energies are: C—H 414 kJ/mol Cl—Cl 243 kJ/mol H—Cl 431 kJ/mol C—Cl 331 kJ/mol
105 kJ released
400
Define molar heat capacity
the energy required to raise the temperature of 1 mole of a substance by 1 ̊C at constant pressure.
400
Name 2 ways to calculate enthalpy (∆H)
1. ∆H = ∆E + P∆V 2. Hess's law 3. Bond dissociation energy 4. ΔH°rxn = Σ ΔH°f (products) minus Σ ΔH°f (reactants)
500
Zinc and sulphur react to form zinc sulphide according to the equation: Zn + S ---------> ZnS If 25.0 g of zinc and 30.0 g of sulphur are mixed, a) Which chemical is the limiting reactant? b) How many grams of ZnS will be formed?
a)Zn b) 0.3803 mol = 37.1g Zn=0.3803 mol S=0.9356 mol
500
Determine what is oxidized and what is reduced in each reaction. Identify the oxidizing agent and the reducing agent, also.
Mg + 2HCl --> MgCl2 + H2 Mg0 to Mg2+; oxidized/red. ag. H1+ to H0; reduced/o.a.
500
Calculate ∆H for the reaction 4NH3 (g)+5O2 (g)→4NO(g)+6H2O(g) GIVEN: N2 (g)+O2 (g)→2NO(g) ∆H=-180.5kJ N2 (g)+3H2 (g)→2NH3 (g) ∆H=-91.8kJ 2H2 (g)+O2 (g)→2H2O(g) ∆H=-483.6kJ
∆H = -1628. kJ
500
Explain what a +w and a -w indicates
+w = work done ON the system by the surroundings -w = work done BY the system on the surroundings
500
A gas is allowed to expand at constant temperature, from volume 1L to 10.1L against an external pressure of 0.50atm. If the gas absorbs 250J of heat from the surrounding, what are the signs of ΔH and w?
ΔH is positive w is negative
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