7: Moles, Mass, Molar Mass
How many molecules are present in 1.75 moles of carbon dioxide, CO2?
Avogadro's constant is 6.02 x 1023
10.5 x 1023 molecules of O
https://tinyurl.com/ytvsd55u
identify the reactant that is oxidized and the reactant that is reduced:
2Fe3+(aq) + Sn2+(aq) --> 2Fe2+(aq) + Sn4+(aq)
Fe is reduced, Sn is oxidized
A sample of nitrogen has a volume of 50.0 L at a pressure of 760 mmHg. What is the volume, in liters, of the gas at 1500 mmHg if there is no change in temperature and amount of gas?
25.3 L
Calculate the grams of solute needed to prepare 1250 mL of a 4.0% (m/v) NH4Cl solution.
50 g NH4Cl
A sample of water has a mass of 59.8 grams. How many moles of water are in the sample?
3.32 moles
A box of table salt, NaCl, contains 737 g of NaCl. How many moles of NaCl are in the box?
12.6 mol NaCl
Balance this equation:
Pb(NO3)2(aq) + NaCl(aq) --> PbCl2(s) + NaNO3(aq)
1, 2, 1, 2
Calculate the new temperature, in degrees Celsius, for the following with n and V constant:
A tank of argon gas with a pressure of 0.950 atm at -18oC is heated to give a pressure of 1250 torr.
14.6 oC
is Pressure and Temperature directly or inversely proportional?
A solution contains 40 mEq/L each of K+ and Cl-. How many moles of each K+ and Cl- are in 1.5 L of the saline solution?
0.06 moles of K+ and Cl-
How many moles of Oxygen (O) are present in 2.5 moles of Al2(SO4)3?
30 moles O
How many atoms of O are in 0.150 mole of aspirin, C9H8O4?
3.61×1023 oxygen atoms
Identify the reactant that is oxidized and the reactant that is reduced:
Cl2(g) + 2NaBr(aq) --> 2NaCl(aq) + Br2(l)
Cl is reduced, Br is oxidized
A gas mixture contains oxygen and argon at partial pressures of 0.60 atm and 425 mmHg. If nitrogen gas added to the sample increases the total pressure to 1250 torr, what is the partial pressure, in torr, of the nitrogen added?
369 torr
The solubility of NaNO3 is 88 g of NaNO3 in 100 g of water at 20 oC. Is the following solution saturated or unsaturated at 20 oC?
11 g of NaNO3 in 25 g of water.
unsaturated
Is the following reaction exothermic or endothermic?
PCl5 (g) ---> PCl3 (g) + Cl2 (g) + 67 kJ
exothermic.
(heat is reactant in endo, for exothermic, heat is product)
When acetylene, C2H2, burns in oxygen, high temperatures are produced that are used for welding metals.
2C2H2(g) + 5O2(g) →→ 4CO2(g) + 2H2O(g)
How many grams of CO2 are produced when 54.6 g of C2H2 is burned?
185 g CO2
Indicate the effect of each factor listed on the rate of the following reaction as increases, decreases, or no change.
2CO(g) + O2(g) --> 2CO2(g)
A. raising the temperature
B. adding O2
C. adding a catalyst
D. lowering the temperature
a. increase
b. increase
c. increase
d. decrease
(rate is increased by more conc. of reactants, higher temperature and adding a catalyst)
What is the number of moles of CO2 in 4000 mL of CO2 gas?
0.179 mol CO2
A 0.1 % (m/v) albumin solution is separated from a 2% (m/v) albumin solution by a semipermeable membrane. (Albumin is a colloid)
a. Which side has higher osmotic pressure?
b. In which direction will water flow to initially?
c. Which side will the volume rise?
b. 0.1% to 2% m/v
c. 2% m/v
The chemical reaction of methane, CH4, and oxygen gas, produces carbon dioxide and water. Write a balanced chemical equation for this reaction.
write on the board. (what type of rxn is this?)
How many oxygen atoms are in 92.0 g of NO2?
2.40 x 1024 atoms O
Acetylene gas, C2H2, is used in welders' torches, and acetylene's combustion produces 2600 kJ of heat.
Write the balanced equation for the combustion of Acetylene (including the heat of the reaction).
Is the reaction exothermic or endothermic?
write on board (2,5,4,2, 2600)
exothermic
(combustion: any CxHxO? compound reacts with oxygen to produce carbon dioxide and water)
In the fermentation of glucose (wine making), 780 mL of gas was produced at 37oC and 1.00 atm. What is the volume (L) of the gas when measured at 22oC and 675 mmHg?
0.836 L
identify the solute as a strong, weak, or non-electrolyte if the following reactions occur when dissolved in water.
https://media.cheggcdn.com/study/aa1/aa169445-d7e4-4be0-82c8-3345f3be9ac6/image.png
N, S, W
What volume of 2.00 M KBr solutions is needed to obtain 3.00 moles of KBr
1.5 liters