Chemistry Conversions Flashcards

Converting Moles to Grams

• Convert moles of a substance to grams by determining the number of moles, calculating the molar mass, and multiplying the two values.

Converting Grams to Moles

• To find moles from grams, divide the mass of the substance by its molar mass.
• Example: For 2 g of water (H2O), with a molar mass of 18 g/mol, divide 2 g by 18 g/mol to get the amount in moles.

Converting Moles to Molecules

• Utilize Avogadro's number (6.02 x 10²³) for conversions: 1 mole equals 6.02 x 10²³ particles (atoms or molecules).
• To convert moles to atoms or molecules, multiply the number of moles by Avogadro's number; for reverse, divide by Avogadro's number.

Converting Molecules to Moles

• One mole corresponds to 6.02 x 10²³ particles.
• Convert moles to molecules by multiplying by Avogadro's number, and convert molecules to moles by dividing by it.

Converting Grams to Molecules

• First, find moles by dividing the number of molecules by Avogadro's number (6.022 x 10²³).
• Then, calculate grams by multiplying the number of moles by the compound's molar mass.

Converting Molecules to Grams

• Start by converting the number of molecules to moles using Avogadro's number.
• Multiply the resulting moles by the molar mass to find the mass in grams.

Calculating Molar Mass of an Element

• Find the average atomic mass (atomic weight) of each element from the periodic table.
• Multiply each atomic mass by the number of atoms in the formula and sum the results for total molar mass.

Calculating Molar Mass of a Compound

• For compounds, add the atomic masses of all constituent atoms.
• Example: The molar mass of NaCl is calculated by summing the atomic mass of sodium (22.99 g/mol) and chlorine (35.45 g/mol).

Calculating Percent Composition

• To find percent composition by mass, calculate the mass of the element and the molar mass of the entire compound.
• Use the formula: (mass of element / molar mass of compound) x 100%.

Calculating an Empirical Formula

• Assume an unknown compound has a mass of 100 g.
• Convert the mass of each element to moles, identify the smallest mole value, and divide all mole values by this number.
• If ratios are not whole numbers, multiply to achieve whole-number ratios, then write the empirical formula.

Setting Up and Solving Bridge Format with Significant Figures

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Differences Between Mass & Molar Mass

• Molar mass indicates the mass of one mole of a substance, measured in grams per mole (g/mol).
• Atomic mass is dimensionless and defined as 1/12 the mass of a carbon-12 atom.