Chemistry: Unit 5 Test Study

when using Scientific Notation if you go <- that way what would be the sign for the answer?

It would be positive

ex of Scientific Notation: 60200000

= 6.02×10⁷

when using Scientific Notation if you go -> that way what would be the sign for the answer?

It would be negative.

ex of Scientific Notation: 0.0002077

= 2.077×10⁻⁴

Mole

6.022×10²³ (Avogadro's Number; one mole of Blah contains that many atoms of Blah)

Molar Mass

Found on The Periodic Table, ex 106.42 g/mol

Atomic Number

Found on Periodic Table; ex 1=H, 2=He

If we had 0.576 what number would we round to for our answer?

the 3rd number because there is only 3 numbers after the . and 0 never counts

Mole Equations:

1) Mass in Grams/molar mass (From periodic table)

2) # of Atoms/(6.022×10²³ Avogadro's #)

Atom Equation:

Moles × (6.022×10²³ Avogadro's #)

If you need to find a certain amount of atoms in that equation what should you do (ex. How many iron atoms does 4.44 moles of Fe₂O₃ contain?)

After you complete the equation for atoms you should then multiply the answer by the # of atoms next to the letter (ex. Fe₂ we would multiply the answer by 2)

Gram Equation:

Moles × Molar Mass (g/mol)

Formula Units Equation:

(Grams/Molar Mass) × (6.022×10²³ Avogadro's #)

Molecule Equation:

(Grams/Molar mass) × (6.022×10²³ Avogadro's number)

Molecule to Gram Equations:

1) Molecule × (Molar Mass / (6.022×10²³ Avogadro's #))

2) Molecules / (6.022×10²³ Avogadro's #) = Moles then Multiply that by molar mass = Grams

Stoichiometry Equation:

Given moles × (want # / Have #)

Note:(want = the # that we want the answer about and have = the number from which we took the moles from)

Stoichiometry Equation for Grams:

(Grams have/Molar mass) × (Want #/Have #) = grams want

(To find) Limiting Factor Equation:

Q. Once you have the limiting factor how do you find the answer of the number needed?

A (given) mol amount × (B coefficient/A coefficient) = B needed amount

Answer: once you get the limiting factor use the same equation to find the answer (use the og limiting factors mole # w/it as a)