2.1.3. Amount Of Substance Flashcards

1
Q

What is the definition of ‘amount of substance’?

A

A measure of the number of entities (atoms, molecules, etc.) in a sample, measured in moles.

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2
Q

What is a mole (symbol ‘mol’)?

A

The unit for amount of substance, defined as containing exactly 6.02 x 10²³ entities.

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3
Q

What is the Avogadro constant (NA)?

A

The number of particles in one mole of a substance, equal to 6.02 x 10²³ mol⁻¹.

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4
Q

What is molar mass?

A

The mass of one mole of a substance, expressed in grams per mole (g mol⁻¹).

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5
Q

What is molar gas volume?

A

The volume occupied by one mole of a gas at room temperature and pressure, expressed in dm³ mol⁻¹.

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6
Q

What are empirical and molecular formulas?

A

Empirical formula: simplest whole number ratio of atoms in a compound.
Molecular formula: actual number and type of atoms in a molecule.

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7
Q

How can you calculate empirical and molecular formulas?

A

Use mass or percentage compositions and relative molecular mass.

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8
Q

What do the terms anhydrous and hydrated mean?

A

Anhydrous: no water of crystallization.
Hydrated: contains water of crystallization.

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9
Q

How can you determine the formula of a hydrated salt?

A

Through percentage or mass composition data.

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10
Q

How do you express concentration in mol dm⁻³ and g dm⁻³?

A

Concentration in mol dm⁻³: moles of solute per volume of solution in dm³.
Concentration in g dm⁻³: grams of solute per volume of solution in dm³.

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11
Q

What is the ideal gas equation?

A

pV = nRT, where p is pressure, V is volume, n is amount of substance, R is the gas constant, and T is temperature.

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12
Q

What is the significance of stoichiometric relationships?

A

They allow calculations based on the ratios of reactants and products in a chemical reaction.

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13
Q

How is percentage yield calculated?

A

(actual yield / theoretical yield) x 100.

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14
Q

What is atom economy?

A

A measure of the efficiency of a reaction in converting reactants into useful products, calculated as (molar mass of desired products / total molar mass of reactants) x 100.

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15
Q

Why is high atom economy beneficial?

A

It reduces waste and improves sustainability in chemical processes.

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