Mole + Avogadro's Number
How many molecules are in 2 moles?
1.204 X 10 ^ 24 molecules
What is the empirical formula of C5H10O5
CH2O
Determine the oxidation number of each atom in the following substances : NF3
N : +3 , F : -1
Balance the following chemical equation : CO + O2 --> CO2
2 CO + O2 --> 2 CO2
How many moles of gas occupy 98 L at a pressure of 2.8 atmospheres and a temperature of 292 K?
11 moles of gas
How many moles are in 1.5 X 10 ^ 20 molecules?
0.00025 moles
A compound is found to contain 63.52% iron and 36.48% sulfur. Find its empirical formula.
FeS
Determine the oxidation number of each atom in the following substances :HIO4
H : +1, I : +7, O : -2
Write the balanced chemical equation of the reaction : when potassium chlorate is heated, it decomposes to form KCl and oxygen gas.
2 KClO3 --> 2 KCl + 3 O2
A 35 L tank of oxygen is at 315 K with an internal pressure of 190 atmospheres. How many moles of gas does the tank contain?
260 moles of gas
How many moles are in 28 grams of CO2?
0.64 moles of CO2
A compound is found to contain 26.56% potassium, 35.41% chromium, and the remainder is oxygen. Find its empirical formula.
K2Cr2O7
For the following balanced redox reaction answer the following questions : 2Fe 2+ + H2O2 --> 2Fe 3+ + 2OH -
a) which element is oxidized?
b) which element is reduced?
a) Fe 2+
b) O in H2O2
From the reaction : B2H6 + O2 --> HBO2 + H20
a) what mass of O2 will be needed to burn 36.1 g of B2H6?
a ) 125 g O2
A sample of oxygen gas occupies a volume of 250. mL at a pressure of 740. torr. What volume will the gas occupy at a pressure of 800. torr if temperature is held constant?
231 mL
What is the mass of 5 moles Fe2O3?
800 g Fe2O3
A 60.00 g sample of tetraethyllead, a gasoline additive, is found to contain 38.43 g lead, 17.83 g carbon, and 3.74 g hydrogen. Find its empirical formula.
PbC8H20
Determine the oxidation number of each of the following atoms in the substances
a) MnO4 -
b) HClO3
a) Mn : +7, O : -2
b) H : +1, Cl : +5, O : -2
From the reaction : B2H6 + O2 --> HBO2 + H20
b) How many moles of water are produced from 19.2 g of B2H6?
b) 1.39 mole of H2O
A sample of helium occupies a volume of 3.8 L at -45 degrees Celsius. What volume will it occupy at 45 degrees Celsius?
5.3 L
Aspartame is an artificial sweetener that is 160 times sweeter than sucrose when dissolved in water. The molecular formula of aspartame is C14H18N2O5.
a) Calculate the molar mass of aspartame.
b) How many moles are in 10.5 g of aspartame?
c) How many atoms of nitrogen are in 1.2 grams of aspartame?
a) 294.34 g/mol
b) 0.036 moles
c) 4.9 X 10 ^ 21 atoms of Nitrogen
Determine the molecular formula of the compound with an empirical formula of CH and a formula mass of 78.110 g.
C6H6
Determine what is oxidized and what is reduced in each reaction :
2 Cs + Br2 --> 2 CsBr
Cs oxidized and Br reduced
2 HCl + Zn --> ZnCl2 + H2
When you use 25 mL of 4.0 M HCl to produce H2 gas, how many grams of Zinc foes it react with?
3.3 g of Zinc
A soda bottle is flexible enough that the volume of the bottle can change when without opening it. If you have an empty soda bottle with a volume of 2.0 L at room temperature (25 degrees Celsius), what volume will the bottle occupy when in the freezer at a temperature of -4.0 degrees Celsius?
1.8 L