Chapter 7.3 and 7.4 Flashcards
The mass of an atom, molecule, or ion is called what?
formula mass (measure in amu)
The mass of the mole of a substance is called what?
molar mass (grams)
1 mole equals how many particles?
6.022 × 10^23
What is the order that you convert masses in?
g – moles – molecules – atoms
molar av’s # subscript
opposite
atoms – moles – grams
What is the Empirical formula?
The Empirical formula is a compound’s formula in it’s lowest whole number ratios.
Are ionic compounds already at their lowest whole number ratios?
Yes
Are covalent compounds already at their lowest whole number ratios?
No
What are the steps to find the Empirical Formula?
- Convert to moles
- Divide each number by the smallest mole number
- Multiply by a factor to get a whole number ratio
What is the Molecular formula?
The molecular formula is a compound’s formula at it’s exact composition. It IS NOT reduced!
To find the Molecular formula, what do you need?
you need the molar mass of the compound
When finding the molecular formula of a hydrate, one of the numbers will always be _.
1
What is Molarity?
Molarity describes the concentration of a substance.
What is molarity’s formula?
moles of solute (stuff being dissolved)
What can you abbreviate Molarity as?
M, mol/l, molar
What is good for prepping a solution?
A volumetric flask
________ decrease concentrations by adding water.
Dilutions decrease concentrations by adding water.
What is the solvent in a dilution?
H20
What is the equation for Molarity for dilutions?
Molarity(i)Volume(i) = Molarity(F)Volume(F)
MiVi = MFVF
What is molality?
Molality is a way to express the concentration of a solution.
What is the formula for molality?
moles of solute
kilograms of solvent (H20)
mol/kg
What can you abbreviate Molality as?
m, mol/kg, molal
Is molarity temperature-dependent?
Yes (technically)
Is molality temperature-dependent?
No
What is the formula for percent composition?
(mass X)
(total mass) x100
When finding the molecular formula, you divide the molar ____ by the empirical’s ____.
When finding the molecular formula, you divide the molar mass by the empirical’s mass.
When finding the significant figures for a problem’s answer, you should refer to the what?
original numbers of the problem
A substance should be diluted by adding ____ to _____, not the other way around.
A substance should be diluted by adding acid to water, not the other way around.
When should the ratio of an element to it’s compound be added to the stoichieometry equation?
The ratio should be added when the question asks for the amount of said element.
