Basic Stoich
___ H2 + ___ O2→ ___H2O, How many moles of water are produced from 4 moles of hydrogen
4 moles
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
Consider the hypothetical reaction:
A --> B ΔH= +30 kJ
B --> C ΔH= +60 kJ
Use Hess's law to calcultate ΔH for A --> C90 kJ
90 kJ
How do you convert to that unit?
Kelvin
Add 273 to whatever celsius was
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
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
Calculate the ΔH for the reaction: Fe + ZnCl2 --> FeCl2 + Zn
Given:
Fe + Cl2 --> FeCl2 ΔH= -3441.8 kJ
Zn + Cl2 --> ZnCl2 ΔH= -415.1 kJ
ΔH= -3026.7 kJ
If something feels cold in your hand, it is likely an ____ process because it is ____ heat to/from your hand.
** Come up with the two words that fill in the blanks.
Endothermic
Taking in
How many grams of CO2 are produced when 10 grams of C3H8 goes through a combustion reaction?
___ C3H8 + ___ O2 --> ________ + __________
30 grams
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
Calculate the ΔH for the reaction:
C(s) + 1/2 O2 -->CO (g)
Given:
C(s) +O2(g)-->CO2(g) ΔH= -393.5 kJ
CO(g) + 1/2 O2(g) -->CO2(g) ΔH= -283.0 kJ
-110.5 kJ
What are the three aspects of "Collision Theory"?
Particles must collide
Collision must have enough energy
Collision must have the correct angle
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
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)
Calculate the ΔH for the reaction: 4NH3 +5 O2--> 4NO + 6H2O
Given:
2NH3 --> N2 + 3H2 ΔH= +92 kJ
2H2O --> 2H2 +O2 ΔH= +572 kJ
N2 + O2 --> 2 NO ΔH= -180 kJ
ΔH= -1892 kJ
Object A has a mass of 25 g at a temperature of 23˚C
Object B has a mass of 50 g at a temperature of 23˚C
The particles of which object have the higher average kinetic energy?
Both have the same average kinetic energy.
Same temp = Average KE
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
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
Calculate ΔH for the reaction: 2ClF3+ 2F2+4O2 --> Cl2O +7 F2O
Given:
Cl2O+ F2O --> 2 ClF +O2 ΔH= -167.4 kJ
4ClF3 + 4O2 --> 2Cl2O + 6F2O ΔH= 682.8 kJ
2 F2 + O2 --> 2 F2O ΔH= -181.7 kJ
ΔH= 333.7 kJ
Write the nuclear symbol for a particle that has...
15 protons, 18 electrons, and 16 neutrons
31P3-