Flashcards in C3 NEW Deck (18)
What is the law of the conservation of mass?
No atoms are lost or made during a chemical reaction. Mass of products = mass of reactants.
Define relative atomic mass (Ar).
The mass of an atom compared to 1/12 of the mass of a carbon-12 atom?
Define relative formula mass (Mr).
The sum of the relative atomic masses of the atoms in the numbers shown in the formula.
How can % by mass of an element in a compound be calculated?
= total mass of element / Mr x100
Why does mass seem to change in some reactions?
One or more of the reactants or products is a gas and the mass of the gas is not often measured.
What is concentration of a solution?
The amount of chemical dissolved in a certain volume of solution.
How is volume in cm3 changed to be in dm3?
Divided by 1000.
What unit is used for mass concentration?
What is the formula used to calculate concentration?
Concentration = mass(g) / volume(dm3)
Why might a reaction not have 100% yield?
-Reaction may be reversible
-Some of product may be lost
-Some of reactants May react differently
What does atom economy measure?
The amount of reactants that end up as useful products in a reaction.
Why are reactions with high atom economy preferred?
Less reactants are needed and have less waste so they are more sustainable and economic.
What is a limiting reagent?
Chemical used up in a reaction that limits the amount of product formed.
How many particles are in a mole of a substance?
The avagadro constant ( 6.02 x |0 23)
What is the formula to calculate moles from mass?
Moles = Mass divided by relative formula mass
How is molar concentration calculated?
Concentration = moles of solute (mol/dm3)
What experimental technique is used to get data to calculate the concentration of a solution?