MP 4 Quarterly Review for Chemistry I

Thermochemistry Unit:

  • Know the definition/concepts of:
  • exothermic and endothermic
  • specific heat
  • calorimetry
  • heat of fusion & heat of vaporization
  • thermochemical equations & stoichiometry (HONORS ONLY)
  • Practice and be able to do problems that involve
  • using q = mC∆T (when there is a temperature change)
  • energy diagrams & thermochemical equations
  • heat curve
  • calorimetry

Solution Unit

  • Know the definition/concepts of:
  • Solute vs solvent
  • Mass percent/percent composition & PPM
  • Molarity
  • Solubility curves – saturated, unsaturated, supersaturated

-two types of problems, subtraction & ratios

-dilutions M1V1=M2V2

  • Electrolytes - definition
  • Colligative properties - # of particles and freezing & boiling point changes
  • Practice and be able to do problems that involve
  • Percent composition
  • PPM
  • Molarity
  • Solubility curve problems
  • Dilution problems

Solutions

  1. What is an electrolyte?
  1. What are the parts of a solution?
  1. What does unsaturated, saturated, and supersaturated mean?
  1. How would you determine if an unknown solution was saturated, unsaturated, or supersaturated? (hint: use some additional solute)
  2. What factors increase the rate of dissolution (how fast the solute dissolves)?
  1. How much .5 M HCl solution can be made by diluting 25 mL of 10 M HCl?
  1. I have 500 mL of a 3.5 M NaCl solution. If I boil off the water until the volume of the solution is 250 mL, what will the molarity of the solution be?
  1. How much water would I need to add to 500 mL of a 5 M KCl solution to make a 1.0 M solution?
  1. What is the effect to the freezing point and boiling point if you add more particles to a solution?
  1. Why does an ionic substance generally have a strong effect than a covalent molecule at changing the boiling point of a solution?
  1. If the mass of the water is 150 g and the mass of salt is 34 g, what is the percent concentration of the salt water?
  1. If you have a solution that is 32%, how many grams of salt are in 400 g of solution?
  1. What is the ppm for a solution that has 0.0098 g of sugar in 780 g of water?
  1. How many moles are in a solution of 4 M in a total of 65 mL?
  1. How many grams are in a solution of salt (NaCl) that has 0.6 M and 1.5 L?
  1. What volume is needed to make a solution of 36 g of KNO3 that is 0.45 M?
  1. What is the concentration of a solution that has 100 g of LiOH in 400 mL of water?

USE A SOLUBILITY CURVE SOLVE THE FOLLOWING

  1. At 20oC, a saturated solution of NaNO3 contains 87 grams of solute in 100 ml of water. How many grams of NaNO3 must be added to saturate the solution at 50oC?
  1. A saturated solution of KClO3is prepared at 60oC using 200.mL of water. How many grams of solute will precipitate out of solution if the temperature is suddenly cooled to 30oC?
  1. Thirty grams of KCl are dissolved in 100 mL of water at 45oC. How many additional grams of KCl are needed to make the solution saturated at 80oC?
  1. What is the lowest temperature at which 40 grams of KNO3 can be dissolved in 100 mL of water?
  1. How much HClat 45oC can be dissolved in 456 mL of water?
  1. Are the following solutions saturated, unsaturated or supersaturated (assume that all three could form supersaturated solutions)
  1. 40. g of KCl in 100 mL of water at 80oC
  2. 120. g of KNO3 in 100 mL of water at 60oC
  3. 80. g of NaNO3 in 100 mL of water at 10oC

Energy & Heat ** Look over chapter 10 notes, but here is a few sample questions

  1. What is an exothermic reaction? What is going on with the energy of the reactants and products?
  1. What is an endothermic reaction? What is going on with the energy of the reactants and products?
  1. What does specific heat capacity mean? What does it mean if the specific heat number is low? What does it mean if the number is high?
  1. Explain the difference between potential and kinetic energy.
  1. What is the significance of the law of conservation of energy
  1. What is the difference between temperature and heat?
  1. Do metals have relatively low or high specific heat capacities? How do you know this?
  1. Determine the final temperature of a 12.6 g aluminum block originally at 22 °C if you lose 456 J of energy to it. (specific heat = 0.89 J/g C)
  1. Suppose you wanted to heat a mug of water (221 mL) from room temperature 24.5 °C to 34 °C to make a cup of tea. How much energy (in units of calories and joules) would you need from your microwave? (Hint: density of water is 1 g/mL and the specific heat is 1 cal/g °C and 4.184 J/g °C)
  1. What is meant by potential energy in a chemical reaction? Where is it located?
  1. In an endothermic reaction, do the reactants or products have the lower potential energy?
  1. What does it mean when energy (“q”) is reported with a negative sign? A positive sign?
  1. If it takes 568 J of energy to warm 17.4 g of water by 17 °C, how much energy would be needed to warm the water by 62.5 °C? (the specific heat of water is 1 cal/g °C and 4.184 J/g °C
  1. If 7.24 kJ of heat is applied to a 952 g block of metal, the temperature increases by 10.7 °C. Calculate the specific heat capacity of the metal in J/g °C.
  1. 35.2 g sample of metal X requires 1252 J of energy to heat the sample by 25 °C. Calculate the specific heat capacity of this metal.
  1. What is Enthalpy?
  1. Explain the difference between potential and kinetic energy. (use an example).
  1. Summarize the law of conservation of energy in your own words.
  1. A 15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes from 25°C to 175°C. Calculate the specific heat capacity of iron.
  2. There are 60 grams water in a calorimeter with an initial temp of 23.5 °C. 2.5 grams of a Dorito is burned and the heat is directed into the water. The final temperature of the water in the calorimeter is 26.7 °C. How many calories are there in each gram of Dorito?

GIVEN:

Cliquid water = 4.18 J/goC

Csolid water= 2.11 J/goC

Cwater vapor = 2.08 J/goC

Hv water = 2260 J/g OR 6.02 kJ/mol

Hf water = 334 J/g OR 40.7 kJ/mol

  1. How much energy does it take to make 180 grams of water 150oC (gas) when you start with it as ice at - 25 oC?
  1. If 100 grams of ice was warmed, melted, & warmed again from -40.0 °C to 25.0 °C, how many kJ were absorbed?
  1. What mass of ice at 0 °C can be melted by using 2.05 kJ?
  1. Write the thermochemical equation and enthalpy diagram (graph) for the synthesis reaction of NH3 forming from its elements. (ΔH = - 22.08 kcals) (HONORS ONLY)
  1. An unknown metal with a mass of 95.2 g is heated to a temperature of 80 °C. It is placed in 24.4 g of water that is at a temperature of 18.5 °C. The temperature of the water and metal then reach a temperature of 34.5 °C. What is the specific heat of the metal?

Equations Needed:
% mass = (g solute / g solution) x 100%
g solution = g solute + g solvent
ppm = (g solute / g solution) x 1,000,000
Molarity (M) = mol / Lmol = M x LL = mol / M 1000mL = 1L
q = mC∆T
∆T = Temp Final – Temp Initial
q=mHf q=mHv
q=nHf q=nHv n = # mols (HONORS ONLY)
M1*V1= M2*V2 /