Chemical Language
What is a chemical formula?
This tells you how many atoms of each element are present in a compound.
What is the change number of atoms of each element across a reaction?
Zero (Law of conservation of mass)
What does 16 depict in 16O?
Atomic mass of oxygen atom
What is the mass of carbon required to make a mole of CO2?
12 g
What does percentage composition mean?
Mass percent of an element per 100 g of the compound
What does the arrow in a reaction mean?
he arrow (→) in a chemical equation represents this "the direction of the reaction” (from reactants to products)
What is not balanced here?
Na + Cl₂ → NaCl
Chlorine
What is the "formula mass" of H2O?
18 grams per mole (unit is required)
If 16 g of oxygen gas reacts with sodium, how many moles of Na2O are formed?
1 mole
What is the percentage contribution of S in SO2?
50%
What is the Law of Conservation of Mass?
This law states that mass is not created or destroyed in a chemical reaction.
What is the total number of reacting hydrogen atoms in a balanced form of the following equation?
H₂ + O₂ → H₂O
4
What is the mass of 2 moles of CO2?
88 g
How many grams of oxygen gas is needed to for one mole of magnesium oxide?
1 mole
What does 80% purity of a compound mean?
80 g of pure substance in present in a 100 g sample
What does (aq) mean?
This symbol tells you that a substance is dissolved in water.
What are coefficients in a reaction?
Coefficients are the number of moles of a substance in a "balanced" equation
Which molecule is heavier - carbon dioxide or HCOOH?
HCOOH
Cu + O2 -> Cu2O
How many grams of copper is required for formation of 1 mole of copper oxide?
127 g
What does 0.9 fraction purity mean?
90% purity of the sample, or 90 g pure substance in a 100 g sample
What does the subscript to the right side of an element's symbol represent?
In a chemical formula, this number shows the ratio in which atoms combine.
Why can't the subscripts of elements can be changed in a chemical formula?
Because that leads to a "different" compound. The number of atoms of a type is fixed in any compound
If a compounds contains 2 atoms of oxygen in a molar mass of 100 g mol-1, what is the percent mass of oxygen in the compound?
32%
A student reacts CaCO3 with HCl, what is the mass of the gas formed per mole of HCl?
22 g
What is the amount of CuSO4 (in mol) required to prepare a 10% by mass solution in water?
Roughly 0.0625 mol