Quantitative chemistry *DOUBLE* Flashcards

1
Q

What is the formula of water?

A

The formula of water is H2O.

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2
Q

What is the formula of sodium chloride?

A

The formula of sodium chloride is NaCl.

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3
Q

What is the formula of carbon dioxide?

A

The formula of carbon dioxide is CO2.

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4
Q

The formula of magnesium chloride is MgCl2. What is the ratio of magnesium ions to chloride ions?

A

The ratio of Mg to Cl atoms in MgCl2 is 1:2.

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5
Q

The formula of sulfuric acid is H2SO4. How many atoms of each element are in the formula?

A

In H2SO4, there are the following numbers of atoms of each element: H = 2, S = 1, O = 4

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6
Q

The formula of calcium nitrate is Ca(NO3)2. How many calcium, nitrogen and oxygen atoms are in the formula?

A

In Ca(NO3)2, there are the following numbers of atoms of each element: Ca = 1, N = 2, O = 6

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7
Q

If sodium chloride has a large 2 in front of it, like this: 2NaCl, how many atoms of each element are there?

A

2NaCl means that there are two atoms of sodium and two atoms of chlorine.

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8
Q

If water has a large 2 in front of it, like this: 2H2O, how many atoms of each element are there?

A

2H2O means that there are four atoms of hydrogen and 2 atoms of oxygen.

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9
Q

There are two numbers alongside chlorine in the periodic table, 17 and 35.5. What does the number 17 represent?

A

atomic number

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10
Q

There are two numbers alongside chlorine in the periodic table, 17 and 35.5. What does the number 35.5 represent?

A

relative atomic mass

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11
Q

Sodium chloride has the formula NaCl. The relative atomic mass of sodium is 23 and that of chlorine is 35.5. What is the relative formula mass of NaCl?

A

The relative atomic mass of NaCl is 58.5 (23 + 35.5).

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12
Q

State the law of conservation of mass.

A

The law of conservation of mass states that no atoms are lost or made during a chemical reaction, therefore: mass pf products = mass of reactants.

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13
Q

A water molecule has the formula H2O. The relative atomic mass of hydrogen is 1 and that of oxygen is 16. What is the relative formula mass of a molecule of water?

A

The relative atomic mass of H2O is 18 ((2x1)+16)

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14
Q

What is the symbol for relative atomic mass?

A

The symbol for relative atomic mass is Ar or RAM.

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15
Q

What is the symbol for relative formula mass?

A

The symbol for relative formula mass is Mr or RFM.

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16
Q

What is the difference between relative atomic mass and relative formula mass?

A

The relative atomic mass of an element is the number of protons + neutrons in the element. The relative formula mass is the of a compound is the sum of relative atomic masses of the atoms in the numbers shown in the formula.

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17
Q

The relative atomic mass of hydrogen is 1. What is the relative formula mass of a hydrogen molecule?

A

The relative atomic mass of a molecule of hydrogen is 2.

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18
Q

A carbon dioxide molecule has the formula CO2; the relative atomic mass of carbon is 12 and that of oxygen is 16. What is the relative formula mass of carbon dioxide?

A

The relative formula mass of a molecule of carbon dioxide is 44.

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19
Q

What is the relative formula mass of magnesium oxide, MgO?

A

The relative formula mass of MgO is 40.

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20
Q

What is the relative formula mass of sulfuric acid, H2SO4?

A

The relative formula mass of H2SO4 is 98.

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21
Q

What is produced when magnesium carbonate is thermally decomposed by heating in an open test tube?

A

magnesium carbonate –> magnesum oxide + carbon dioxide MgCO3 –> MgO + CO2

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22
Q

A sample of magnesium carbonate was heated in an open test tube. Why did it lose mass?

A

Magnesium carbonate lost mass because gas, specifically carbon dioxide, escaped.

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23
Q

What is produced when magnesium reacts with oxygen?

A

magnesium + oxygen –> magnesium oxide 2Mg + O2 –> 2MgO

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24
Q

A sample of magnesium was heated. Why did it gain mass?

A

The magnesium gained mass because it reacted with oxygen atoms in the air forming magnesium oxide. The mass of magnesium oxide is greater than the mass of magnesium because oxygen atoms have been gained.

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25
Q

A sample of copper carbonate was heated in an open test tube. Why did it lose mass?

A

Copper carbonate lost mass because gas, specifically carbon dioxide, escaped.

26
Q

How many cm3 are there in 1 dm3?

A

1000

27
Q

State how to convert cm3 in to dm3.

A

Convert cm3 in to dm3 by dividing by 1000

28
Q

State how to convert dm3 in to cm3.

A

Convert cm3 in to dm3 by multiplying by 1000

29
Q

What is 250 cm3 expressed in dm3?

A

0.25

30
Q

What is 0.5 dm3 expressed in cm3?

A

500

31
Q

100 cm3 of a solution contained 2 g of salt. What is the concentration of the salt in g/dm3?

A

100cm3 = 0.1dm3. concentration = mass/volume = 2g/0.1dm3 = 20g/dm3.

32
Q

100 cm3 of a solution contains 1.5 g of salt. What is the concentration of the salt solution in g dm3?

A

100cm3 = 0.1dm3. concentration = mass/volume = 1.5g/0.1dm3 = 15g/dm3.

33
Q

250 cm3 of a solution contains 5 g of sugar. What is the concentration of the sugar solution in g dm3?

A

250cm3 = 0.25dm3. concentration = mass/volume = 5g/0.25dm3 = 20g/dm3.

34
Q

A solution of copper sulfate has concentration 10 g dm3. What mass of copper sulfate will be dissolved in 100 cm3 of solution?

A

100cm3 = 0.1dm3. mass = concentration x volume = 10 x 0.1 = 1g

35
Q

2 g of hydrogen reacts with oxygen to form 18 g of water. What mass of water will be formed from 1 g of hydrogen?

A

9g of water will be produced from 1g of hydrogen.

36
Q

2H2 + O2 –> 2H2O. How many molecules of hydrogen are needed to react with 1 dozen molecules of oxygen to form water?

A

2 dozen

37
Q

What is the symbol used for the mole, the unit for amount of substance?

A

mol

38
Q

How many particles are there in 1 mole of particles?

A

6.02 x 1023

39
Q

How many atoms are there in 1 mole of atoms?

A

6.02 x 1023

40
Q

How many molecules are there in 1 mole of molecules?

A

6.02 x 1023

41
Q

How many ions are there in 1 mole of ions?

A

6.02 x 1023

42
Q

How many atoms are there in 1 mole of potassium?

A

6.02 x 1023

43
Q

How many molecules are there in 1 mole of water?

A

6.02 x 1023

44
Q

How many carbon atoms are in 1 mole of carbon?

A

6.02 x 1023

45
Q

How many molecules are there in 1 mole of carbon dioxide?

A

6.02 x 1023

46
Q

Interpret the following equation in terms of moles: Mg + 2HCl –> MgCl2 + H2

A

Mg + 2HCl –> MgCl2 + H2 can be interpreted as 1 mole of magnesium (Mg) reacts with 2 moles of hydrochloric acid (HCl) to produce 1 mole of magnesium chloride (MgCl) and one mole of hydrogen gas (H2).

47
Q

The mass of 1 mole of carbon atoms is 12 g. What is the mass of 2 moles of carbon atoms?

A

24 g

48
Q

What is the formula for calculating the number of moles of substance from its mass in g

A

moles = mass (g) / Ar or Mr

49
Q

Each water molecule contains three atoms. How many moles of atoms are there in 2 moles of water molecules?

A

2 moles of water contains 6 moles of atoms (2 moles of hydrogen atoms and four moles of oxygen atoms).

50
Q

The relative formula mass of chlorine gas is 71. What is the mass of 1 mole of chlorine gas?

A

71 g

51
Q

What is the Avogadro number?

A

6.02 x 1023 the number of atoms/particles in a mole

52
Q

What is the law of conservation of mass?

A

total mass of reactants = total mass of products

53
Q

What mass of water should be formed when 2 g of hydrogen reacts with 16 g of oxygen?

A

2g of hydrogen plus 16g of of oxygen will produce 18 g of water.

54
Q

What mass of magnesium oxide should be formed when 2.4 g of magnesium reacts with 1.6 g of oxygen?

A

2.4g of magnesium and 1.6g of oxygen will react to form 4.0 g of magensium oxide.

55
Q

What is the mass of 1 mole of sodium chloride, NaCl?

A

The mass of 1 mole of sodium chloride is 58.5 g.

56
Q

What is the mass of 0.1 mole of sulfur dioxide, SO2?

A

The mass of 0.1 mole of sulfur dioxide is 6.4 g.

57
Q

What is the relative formula mass of calcium hydroxide, Ca(OH)2?

A

The relative mass of Ca(OH)2 is 74.

58
Q

What is the relative formula mass of magnesium nitrate, Mg(NO3)2?

A

The relative mass of Mg(NO3)2 is 148.

59
Q

In a chemical reaction, why is an excess reactant often used?

A

An excess reactant is used to ensure that all of another reactant is used in the reaction.

60
Q

What is a reactant that is completely used up in a chenical reaction called?

A

The reactant that is completely used up is called the limiting reactant because it limits the amount of products that can be produced.