Chemical Quantities Flashcards
Define element
A substance made of only one type of atom, e.g. sodium
Define compound
A substance made of more than one type of atom, chemically joined together, e.g. carbon dioxide
What is the state symbol for a solid?
(s)
What is the state symbol for a liquid?
(l)
What is the state symbol for a gas?
(g)
What is the state symbol for a solution?
(aq)
Define conservation of mass
The mass of the reactants and products is equal, no mass is lost or gained during a reaction
What is a balanced symbol equation?
A symbol equation with equal numbers of each element for both products and reactants
How many hydrogen atoms are present in H2?
Two
How many oxygen atoms are there in CO2?
Two
Why do some reactions appear to lose mass?
At least one of the products is a gas, and is lost to the environment
Why do some reactions appear to gain mass?
At least one of the reactants is a gas, and is taken from the environment
What is the relative atomic mass of a substance?
The mass of an element compared to the mass of the Carbon-12 isotope
What is the relative atomic mass of oxygen, O2?
16
What is the relative formula mass of a substance?
The sum of all the relative atomic masses of the atoms in a compound
What is the relative formula mass of CO2?
44
How do you calculate the percentage by mass in a compound?
(Relative atomic mass/Relative formula mass) x 100
What is the percentage by mass of hydrogen in H2O?
11.10%
What is a limiting reactant?
The reactant that is completely used up during a reaction
How do you calculate the mass of a reactant or product from a balanced symbol equation?
Calculate the relative atomic of formula mass of known substances, Calculate the number of moles of known substances, Calculate the ratio of moles, Calculate the mass
What is a mole?
An amount of a substance which contains 6.02 x 10^23 atoms, ions or molecules
What is the Avogadro constant?
6.02 x 10^23
State the equation to calculate the number of moles
Number of moles = Mass / Relative atomic or relative formula mass
Define concentration
The mass of a solute dissolved in a given volume of a solvent
What are the standard units for concentration?
g/dm3
Define solute
A solid which dissolves into a solvent
Define solvent
A liquid into which a solute dissolves
Define solution
A mixture of solute and solvent
How many cm3 are there in 1 dm3?
1000
What is the equation for calculating concentration, mass and volume?
Concentration = Mass / Volume
