Ch3: CHEMISTRY FUNDAMENTALS Flashcards
(41 cards)
What does a mole measure? What is its abbreviation?
Amount of substance
mol
What does an ampere measure? What is its abbreviation?
Electric current
A
What are the six SI base units?
Meter (m)
Kilogram (kg)
Second (s)
Mole (mol)
Kelvin (K)
Ampere (A)
What do prefix symbols m and M represent ?
Milli and Mega
1000L = ___ m³
1
1L = ___cm³
1000
1mL = ___ cm³= ___ cc
1 and 1
What is an angstrom? what is its abbreviation? What does it measure?
abbreviated Å
Measures length
Unit of length equal to 10^ -10m
What is an order of magnitude?
An order of magnitude is an approximation of of the logarithm of a value relative to some contextually understood reference value.
Often is the power of 10 a number is raised to when its in scientific notation
for ex. the order of magnitude for 19, 400 would be 4
Density equation
Density= Mass/ Volume
What are the units of density?
Most often kg/m³
In chemistry its more often g/cm³
kg/m³ —–> g/cm³
divide by 1000
g/cm³ —–> kg/m³
Multiply by 1000
Define molecule
When two or more atoms form a covalen bond
Molecular formula
A compounds molecular formula gives the identities and numbers of the atoms in the molecule
Empirical Formula
A formula for a compound in which the number of atoms in each element in the compound are represented by the lowest whole number ratio
What is the empirical formula for C2H6O2?
CH3O
Formula/ molecular weight. Whats the difference.
Formula weight: Sum of atomic weights of all the atoms in the molecule
Molecular weight typically used when a compound exists as discrete molecules
Atomic mass unit
amu
Is the atomic mass that is listed for each element on the periodic table
What is a mole? What is the number that represents a mole?
A particular number of things
mole= 6.02 x 10²³ entities
This is avogadros number
If an atom of sodium has a mass of 23 amu, 1 mole of sodium atoms has a mass of ___g
23
Whats the formula/ what are the steps for calculating the percentage composition by mass in a compound?
Calculate the total molecular weight of the compound
Calculate the weight of each element to see their contribution to the total mass in g
% of the element= Mass of the element / Total mass of compound
Which contains more formula units; a 1-mole sample of potassium dichromate or a 1 mole sample of lead azide?
Trick question, both samples contain the same number of formula units, namely 1 mole of them
How would you mathematically approach this question?
What is the empirical formula of a compound that is, by mass, 90% Carbon and 10% Hydrogen?
Assume the compound is 100g. 90g carbon, 10g hydrogen
Calculate the number of moles of Carbon if there are 90g of Carbon, and 1 mole of Carbon is 12 g/mol.
#moles of C: 90g / 12g/mol
#moles of H: 10g / 1g/mol
Perform ratio of amount of C to amount of H
15/2 / 10 = 15/20 = 3/4
Thus C3H4
