Moles
Definition
A mole is unit for measuring matter at atomic level. One mole contains exactly 6.02214076×10²³ particles, such as atoms, molecules, or ions.
Analogy
Consider moles as "dozens" but on an atomic scale. Just like dozen represents 12 items whether they are eggs or donuts; similarly mole represents Avogadro's number of particles whether they are atoms or molecules.
Related terms
Avogadro's Number: The number of particles in one mole, approximately 6.022 x 10^23.
Molar Mass: The mass (in grams) of one mole of a substance.
Stoichiometry: The calculation of quantities in chemical reactions using moles.
"Moles" appears in:
Study guides (1)
Practice Questions (10)
- Consider a reaction between magnesium and Iron (III) Oxide. If 4 moles of magnesium oxide was produced, how many moles of magnesium was reacted?
- How many moles of electrons are transferred when 2mol of Mg reacts with 2mol Br₂ to produce 2mol MgBr₂?
- A solution contains 500 mL of 1 M acetic acid. How many moles of sodium acetate must be added to achieve a pH of 5.75? (pKa = 4.75)
- How many moles of 0.75 M HCl must be added to 120 mL of 0.90 M sodium formate to make a buffer of pH = 4.00? (pKa = 3.75)
- You need to prepare a buffer solution of pH 4.178 from 25.0 mL of 0.282 M solution of a sodium salt of a weak acid, NaA where the pKa of the weak acid HA is 4.270. How many moles of 0.329 M HCl do you need to add to achieve this goal?
- How many moles of O₂ are in 16 grams of oxygen gas?
- How much would 5.5 moles of calcium chloride (CaCl₂) weigh?
- The reaction A⇌B+2C is known to only start with 0.8 moles of A in a container of 1 liter. The reaction occurs and it is found that there are only 0.25 moles of A left once equilibrium is reached. Which of the following shows the concentration of C at equilibrium?
- The rate of the forward reaction is known to be 0.4 M over a certain period of time. Furhtermore, the reaction only started with the necessary reactants. If one of the products has three moles in the reaction, what will be the net change in concentration?
- How many moles of solute are in 500.0 mL of a 0.250 M NaCl solution?
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