1 Stochiometry Flashcards

1
Q

What is the main difference between a compound and a mixture?

A
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2
Q

What is the difference between a liquid (l) and an aqueous solution (aq)

A

Liquid is a pure element or compound such as water.

Aqueous solution refers to a substance (or solution) dissolved in water.

NaCl(aq) is a solution of sodium chloride in water.

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3
Q

A change from gas to solid is called…

A
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4
Q

A change from solid to gas is called

A
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5
Q

The difference between evaporation and boiling is, that…

A

… boiling happens at the boiling point

… evaporation happens between the melting point and the boiling point.

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6
Q

Calculate the molar mass of

C6H12O6

A

6(12.01) + 12(1.01) + 6(16.00)

= 180.18 g mol-1

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7
Q

Calculate the molar mass of

(NH4)2SO4

A

2(14.01) + 8(1.01) + 32.07 + 4(16.00)

= 180.18 g mol-1

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8
Q

What symbol and unit has the relative atomic mass.

A

(Ar) - no unit

Relative atomic mass or atomic weight is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a given sample to one unified atomic mass unit.

The unified atomic mass unit is defined as being ​1⁄12 of the atomic mass of a carbon-12 atom.

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9
Q

Molecules have relative ….. masses.

Ionic compounds have relative ….. masses.

A

Molecules have relative molecurar masses.

Ionic compounds have relative formular masses.

Abbreviation: Mr

No unit, dimensionless

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10
Q

0.100 mol of (NH4)2SO4

represents :

a. ____ mol of ammonium ions
b. ____ hydrogen atoms
c. ______ atoms in total

A

a. 0.100 x 2 = 0.200 mol of ammonium ions (NH4)
b. 0.100 x (4x2) x 6.02 x 1023 hydrogen atoms
c. 0.100 x 15 x 6.02 x 1023 atoms

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11
Q

What mass of sodium chloride is produced when chlorine reacts with 52.60 g of sodium Iodide?

A
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12
Q

Calculate the amount (in mol) in

this 8.80 g of carbon dioxide, CO2

A

0.200 mol

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13
Q

You shall find the number of a specific atoms in a substance which mass is given in kg?

What are the steps to calculate it?

A
  1. Convert the mass of the substance into grams (g).
  2. Calculate the amount of substance in mol, considering all atoms and using the formular n = m (g) / molar mass
  3. Consider the number of specific atoms in the substance (for instance H2O has 2 Hydrogen atoms) and mulitply by the molar to have number of atoms in mole
  4. Multiply with the Avogadro constant of 6.02 x 1023 to get the number of atoms.
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14
Q
A
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