Chemistry - Unit 8 Quiz

1 mole defines:

• the number of atoms in 1 molecule

• the molar mass of 1 molecule

• the amount of a substance

• All answers are correct

The coefficients of a balanced equation tell us:

• the number of grams of that substance

• the ratio of moles of each substance in a chemical equation

• the number of molecules of a substance that are needed for a reaction to occur

• the number of molecules of a substance that will be produced if a reaction occurs

The number of atoms in 1 mole of a substance is called:

• Avagadro's number

• molecular mass

• the coefficients

• nothing, there is no such thing

Stoichiometry is a method of:

• calculating the molecular weight of a molecule

• finding the amounts of reactants and products in a reaction

• calculating the amount of energy used or released in a reaction

• determining if a reaction will proceed or not

The molar mass of a molecule is:

• the atomic mass units of the molecule

• the number of atoms in a molecule

• the combined weight in grams of the atoms in the molecule

• coefficient of the molecule

Calculate the number of grams of sulfur that would be found in 82.4 moles

• 0.389 grams

• 2.54 grams

• 2642 grams

• 1 gram

Calculate the number of moles of oxygen in 5.54 x 10²⁵ atoms.

• 92.0 moles

• 3.34 x 10⁴⁹ moles

• 0.0109 moles

• 3.46 x 10²⁴ moles

Given N₂ + 2O₂ + 67.8 kJ --> 2NO₂, calculate the number of atoms of N₂ needed to produce 85 g of NO₂

• 2.55 x 10²⁵ atoms N₂

• 0.924 atoms N₂

• 1.11 x 10²⁴ atoms N₂

• 5.56 x 10²³ atoms N₂

Given N₂ + 2O₂ + 67.8 kJ --> 2NO₂, calculate the amount of energy needed if 88 g of O₂ is burned.

• 41.5 kJ

• 93.2 kJ

• 186 kJ

• 190925 kJ