L4 - Chemical Equations, The Mole & Molarity Flashcards
What is the Mole?
The SI unit for amount of substance.
Define Avogadro’s Number (NA).
The number of atoms found in 12g of Carbon-12.
What is 1 Mole?
6.0221367 * 10^23
What is the mass of 1 mole of any substance?
Mass of 1 Mole of any substance is its relative atomic mass (elements) or relative molecular mass (compound) expressed in grams.
Define Molar Mass.
Mass of one mole of a substance.
How do you calculate the Number of Moles using mass?
Number of Moles (mol) = Mass (g) / Molar Mass (g mol-1)
n = m / mm
For any molecule: Molecular Mass (amu) = _____ ____ _______.
Molar Mass (grams)
State the Ideal Gas Law.
“1 mole of any gas occupies the same volume at standard temperature and pressure.”
At STP, Molar Gas Volume is always V = ___________.
22.4 L / 22.4 dm^3 mol^-1
How do you calculate the Number of Moles using volume?
Amount of Substance (mol) = Volume (dm^3) / Molar Volume (dm^3 mol^-1)
n = V / MV
State the Ideal Gas Law mathematically.
pressure (Pa) * volume (m^3) = number of moles (mol) * gas constant (J mol^-1 K^-1) * temperature (K)
PV = nRT
What is the gas constant?
R = 8.314 J mol^-1 K^-1
What is the IUPAC defined Standard Temperature?
273 K
What is the IUPAC defined Standard Pressure?
100 kPa
What is the IUPAC defined Standard Room Temperature?
298 K
Define Molarity.
Solution concentration expressed as moles of solute dissolved in one litre of solution.
How do you calculate Molarity?
Molarity (mol L^-1) = Moles (mol) / Volume (L)
M = n / V
What is the calculation for unknown concentration and volume of solutions?
concentration 1 * volume 1 = concentration 2 * volume 2
c1 v1 = c2 v2
How many litres is 1 ml?
1 ml = 1 / 1000 L
How many grams is 1 mg?
1 mg = 1 / 1000 g
What do chemical reactions involve?
- Changes in identity of compounds
- Energy changes
- Breaking and making chemical bonds
- Rearrangement of valence electrons
How can chemical reactions be described by chemical equations?
- Symbols represent elements
- Formulae describe composition of compounds
- Equations show changes in compounds
What does a coefficient represent?
Coefficient represents number of molecules of compound / atom needed in reaction.
What can coefficients be changed to achieve?
Coefficients can be changed to achieve mass balance but subscripts are never changed to balance an equation.
Subscripts indicate the number of bonded atoms in a molecule.
Changing the subscripts changes the compound.
Define Yield.
Amount of product produced.
How is percentage yield calculated?
Percentage Yield = Actual Yield / Theoretical Yield * 100%
Matter cannot be _______ or ____ in a closed system.
Matter cannot be created or lost in a closed system.
