Basic Stoich
___ H2 + ___ O2→ ___H2O, How many moles of water are produced from 4 moles of hydrogen
4 moles
If you have 5 moles of N2 and 10 moles of H2, how many moles of NH3 can you produce?
N2+ 3H2→2NH3
6.67 moles NH3
50 pts: Pressure is caused by ______
50 pts: Temperature and Pressure have a direct relationship because...
1. Collisions
2. As temperature increases, particles have more energy, meaning they'll move fast, meaning they'll collide harder/more often
If the pressure of a gas is doubled, what would have happened to its volume?
** Assume temperature and amount of gas is constant
Volume was cut in half
What, generally, does the specific heat of a substance tell us?
* How easy or hard it is to change a substance's temperature
** How much energy must be gained or lost to change a substance's temperature
*** How many JOULES of energy must be gained or lost in order to change the temperature of ONE GRAM of substance by ONE DEGREE CELSIUS
How many grams of silver would we be able to produce if we reacted 10 grams of copper with excess silver nitrate?
___ Cu + ___ AgNO3 -->___ Ag + ___ Cu(NO3)2
33.95 grams Ag
What are the steps you'd use to determine what reactant is limiting in a reaction?
** Assume you have masses of both reactants
1. Convert grams to moles of reactant
2. Convert moles of reactant to moles of product
3. Compare moles of product
4. Whichever reactant made less is the limiting reactant
*** The lesser amount is not the limiting reactant.
When 85.0L of a gas at 104.4 kPa is decreased to 21.0kPa, this is the new volume.
What is 423L
If 5 moles of an ideal gas are at 300 K and occupy a volume of 40 L, what is the pressure?
3.08 atm
Calculate the heat absorbed by 150 g of water when it is heated from 20°C to 80°C.
** Specific heat of water is 4.184 J/g˚C
37656 J
How many grams of CO2 are produced when 10 grams of C3H8 goes through a combustion reaction?
___ C3H8 + ___ O2 --> ________ + __________
30 grams
How many grams of Al2O3 can you make if you have...
** 20 grams of Al and 30 grams of O2
____Al + ____ O2 --> ____ Al2O3
37.74 g
** Al is limiting
P1 = 740 kPa
T1 = -73˚C
T2 = 27˚C
Solve for P2
1110 kPa
A container has 4 moles of gas A, 2 moles of gas B, and 2 moles of gas C. What is the partial pressure of gas B if the total pressure in the container is 1.5 atm?
1.5 atm/8 molestotal*2 molesgas b --> 0.375 atm
Calculate the heat released when 250 g of iron cools from 100°C to 25°C.
Specific heat of iron is 0.451 J/g˚C
8475.1 J
You have 50 grams of aluminum reacting with excess oxygen to form aluminum oxide.
** 200 - Write the balanced chemical equation for the reaction (ignore phases)
** Calculate how many grams of aluminum oxide can be produced from 50 grams of aluminum.
1. 4 Al + 3 O2 --> 2 Al2O3
2. 94.48 grams Al2O3
How many grams of the excess reactant are left over when you have...
** 28 grams of N2 and 12 grams of H2
____N2 + ____ H2 --> ____ NH3
** Label which reactant it is!
Approximately 5.93 grams of H2
A gas occupies 12.3 L at 10˚C. What temperature (in ˚C) would the gas need to be cooled to in order to decrease the volume to 4.5 L?
103 K --> -169˚C
If we have 36 liters of neon at STP, how many grams of helium do we have?
36 L/ 22.4 L --> 1.61 moles --> 32.14 grams
300 Points: If 100 g of copper absorbs 250 J of heat, what is its temperature change when it is placed in 100 grams of water? (Specific heat of Copper = 0.385 J/g˚C)
100 Points: Would the temperature change of water be the same?
300: 6.49°C
100: NO (different specific heat values
If we have 65 mL of water, how many molecules of water do we have?
65 mL = 65 grams = 3.61 moles = 2.17x1024 molecules
What are the steps you'd use to determine what how much of an EXCESS reactant is left over in a reaction?
** Assume you have masses of both reactants
1. Convert grams to moles of reactant
2. Convert moles of reactant to moles of product
3. Compare moles of product
4. Convert the mass of which reactant made less into grams of the excess reactant. (THis is how much would be used)
5. Subtract: Original mass minus mass used. Difference is the amount left over
A container with a volume of 25.47 L holds 1.050 mol of oxygen gas. What is the volume if 7.210 grams of oxygen gas is removed from the container, assuming the pressure and temperature remain constant?
20.0 L
A 25.0 g sample of carbon dioxide gas is contained in a 3333 mL container at a temperature of 30.0 °C. Calculate the pressure of the gas in the container using the ideal gas law.
1. 25.0 g/44.01 g --> 0.57 moles
2. 3333 mL --> 0.333 L
3. 30˚C --> 303 K
4. P(3.333L) = (0.57 mol)(0.08206)(303K)
Answer: 4.24 atm
750 points: (This is a calculation that you'll do in lab after MEA)
A 15 gram piece of metal that started at 100˚C is put into a styrofoam cup with 35 grams of water that starts at 25˚C. Together, they reach a temperature of 38 ˚C. What is the specific heat of that metal?
** Specific heat of water = 4.184 J/g˚C
∆TH2O = 13˚C
Qwater = 4.184*13*35 = 1903.72 J
Qmetal = -1903.72 J
cmetal = -1903.72 J/(-62˚C)/15g --> 2.05 J/g˚C