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SA 1 Flashcards

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1
Q

How many oxygen atoms are present in 0.050mol of Al2O3?

A
  1. multiply 0.050 with 3 (3 O atoms)
  2. multiply with the avogadro
    9.0 x 10^22
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2
Q

What is the correct systematic name for Ca(NO2)2?

A

Calcium nitrite

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3
Q

What is the molar mass of (NH4)3PO4? (with units)

A

149.0 g mol^-1

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4
Q

Balance the equation:
x Fe2(SO4)3 + y KOH → z K2SO4 + w Fe(OH)3

A

x = 1, y = 6, z = 3, w = 2

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5
Q

2NaOH + H2SO4 → Na2SO4 + 2H2O
75.00 mL of 0.625 M sodium hydroxide is required to titrate a 100.0 mL solution of sulfuric acid. What is the concentration of the
sulfuric acid?

A
  1. find the mol of NaOH by n = cV (rmb litres)
  2. NaOH is twice of H2SO4, find mol of H2SO4 by multiplying it by 1/2
  3. find conc of H2SO4 by c = n/V (litres)
    0.234 M
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6
Q

2Ni2O3(s) → 4Ni(s) + 3O (g)
If 5.00 mol of Ni2O3 is decomposed to form 1.40 x 10^2 g of Ni, what is the percentage yield of Ni?

A
  1. you know the theory (140), find actual
  2. 5 mol of 2Ni2O3 = 10 mol of 4Ni
  3. find m with 10mol x Mr
  4. actual/theory x 100
    23.9%
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7
Q

2CH3OH(g) + 3O2 (g) → 2CO2(g) + 4H2O(g) ΔH = –1452 kJ mol
How much energy is released when 0.500 mol of oxygen is burnt in excess methanol?

A
  1. 3O2 becomes 0.5mol - multiplier is question/actual (0.5/3)
  2. energy is ΔH x multiplier
    - 242 kJ (exothermic, energy released)
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8
Q

C(s) + O2(g) → CO2(g) ΔH = -394.0 kJ mol
2CO(g) + O2(g) → 2CO2(g) ΔH = -283.0 kJ mol
What is the enthalpy change (ΔH) for the following equation?
C(s) + 1/2O (g) → CO(g)

A

write out equations
1. C + O2 –> CO2
2. CO2 –> CO + 1/2O
-252.5 kJ mol–1

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9
Q

What is Na3N?

A

sodium nitride

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10
Q

What is Ca3P2?

A

calcium phosphide

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11
Q

What is Na2CO3

A

sodium carbonate

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12
Q

What is Cl2O7?

A

dichlorine heptaoxide

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13
Q

What is H2SO3?

A

sulfurous acid

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14
Q

What is SO32-?

A

sulfite

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15
Q

3.65 g of an oxide of carbon was found to have 2.08 g of carbon. Calculate the percentage by mass of carbon in the compound.

A
  1. % comp = want/total x 100
  2. 2.08 / 3.65 x 100
    57%
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16
Q

What is the mass of 1.25 x 1024 atoms of silver?

A

2.24 x 102 g

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17
Q

What is the correct formula for nitrous acid?

A

HNO2

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18
Q

What is the correct name of H2CO3?

A

carbonic acid

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19
Q

What is the correct name of Na2HPO4?

A

sodium hydrogenphosphate

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20
Q

What is the mass of 1.25 x 1024 atoms of silver?

A
  1. divide with avocado
  2. get mass
    2.24 x 102 g
21
Q

How many moles of hydrogen atoms are there in 43.0 g of pentanol, C5H11OH?

A
  1. find mol
  2. mol x atoms (12 H atoms wanted)
    5.86 mols
22
Q

What is the number of oxygen atoms present in 14 g of hydrated sodium carbonate, Na2CO3.10H2O?

A
  1. convert to atoms
    3.8 x 10^23 atoms
23
Q

What is the number of moles of chloride ions in 3.85 g of FeCl3?

A

0.0712 mol

24
Q

A compound with the empirical formula HO has a molar mass of 34 g mol−1. What is its molecular formula?

A
  1. molecular formula = molar mass/Mr
    H2O2
25
Q

An organic compound is known to contain only carbon, hydrogen and oxygen. The compound contains, by mass, 39.1% of carbon and 8.7% of hydrogen. The number of carbon atoms in the empirical formula is

A
  1. divide with each Mr
  2. divide with smallest
    3
26
Q

What is the percentage composition of sulfur in As2S3?

A
  1. Mr of S / Mr total
    39.1%
27
Q

Calculate the mass of barium carbonate produced when excess carbon dioxide is reacted with 0.205 mol of barium hydroxide according to the equation:

Ba(OH)2 + CO2 → BaCO3 + H2O

A

40.4g

28
Q

Lead(II) carbonate decomposes to give lead(II) oxide and carbon dioxide as represented by the following equation:

PbCO3(s) → PbO(s) + CO2(g)

How many grams of lead(II) oxide will be produced by the decomposition of 2.50 g of lead(II) carbonate?

A

2.09g

28
Q

Lead(II) carbonate decomposes to give lead(II) oxide and carbon dioxide as represented by the following equation:

PbCO3(s) → PbO(s) + CO2(g)

How many grams of lead(II) oxide will be produced by the decomposition of 2.50 g of lead(II) carbonate?

A

2.09g

29
Q

What volume (in mL) of 2.5 % (w/v) salt solution would contain 1.8 g of salt?

A
  1. c = w/v x 100 (in ml)
  2. answer / 100
    72 mL
30
Q

7.00 mL of a solution of phosphoric acid, H3PO4, neutralised 1.00 x 102 mL of 0.531 M NaOH solution according to

H3PO4(aq) + 3NaOH(aq) → Na3PO4(aq) + 3H2O(l)

The concentration of the acid is

A
  1. use c1v1 = c2v2
  2. rmb to divide 3

2.53 M

31
Q

Carbon monoxide can be oxidised to carbon dioxide.

2CO(g) + O2(g) → 2CO2(g)

3 mol of CO and 2 mol of O2 are mixed. When the reaction is complete, how many mols of O2 will be left?

A

0.5 mol O2 unreacted.

32
Q

Given the following unbalanced equation. How many moles of Ag2S can be produced when 3.0 mol of Ag, 3.0 mol of H2S and 3.0 mol O2 react?

Ag + H2S + O2 → Ag2S + H2O

A
  1. 4Ag + 2H2S + O2 → 2Ag2S + 2H2O
    1.5 mol
33
Q

Which reactant in the following reaction is in excess when 15 g of Ca(OH)2 is reacted with 15 g of H3PO4

3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O

A

H3PO4

34
Q

The reaction of 5.0 g of fluorine with excess chlorine produced 5.6 g of ClF3. What percentage yield of ClF3 was obtained?

Cl2 + 3F2 → 2ClF3

A
  1. find Mr of F2
  2. multiply n(F2) with 2/3
  3. multiply with Mr of ClF3 (theory
  4. 5.6 / theory
    69 %
35
Q

18.0 g of magnesium is added to 0.200 L of 2.00 M HCl. The following equation represents the reaction that occurs:

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

What is the mass of magnesium that is left behind when all the HCl reacts?

A

-13.1 g.-

36
Q

Hydrogen and chlorine can be produced from sodium chloride according to the following reaction. If this process is 65.0% efficient then how much chlorine could be produced from 96.5 g of sodium chloride?

2NaCl + 2H2O → 2NaOH + H2 + Cl2

A

-38.1 g-

37
Q

What is the percent yield of CO2 if a reaction between 10.0 g CO with 10.0 g O2 produces 12.8 g CO2?

2CO + O2 → 2CO2

A

81.5 %

38
Q

A chemical reaction has a ΔH of −150 kJ mol–1 and the activation energy for the reverse reaction is +350 kJ mol–1. The activation energy, in kJ mol–1, of the forward reaction is

A

200

39
Q

C(s) + O2(g) → CO2(g) ΔH = –393.5 kJ mol–1

2H2(g) + O2(g) → 2H2O(l) ΔH = –571.6 kJ mol–1

Given the information above, what is the enthalpy change for the reaction represented by the following equation?

C(s) + 2H2O(l) →CO2(g) + 2H2(g)

A

+178.1 kJ mol–1

40
Q

The decomposition of water can be represented by the following thermochemical equation

2H2O(l) → 2H2(g) + O2(g) ∆H = + 571.8 kJ mol−1

From this equation, it can be concluded that the formation of two moles of liquid water from gaseous hydrogen and oxygen is an

a. exothermic process releasing 571.8 kJ of heat energy.

b. exothermic process releasing 1143.6 kJ of heat energy.

c. endothermic process absorbing 571.8 kJ of heat energy.

d. endothermic process absorbing 1143.6 kJ of heat energy.

A

a. exothermic process releasing 571.8 kJ of heat energy.

41
Q

What does a catalyst do in a reaction?

A

It provides an alternative pathway of lower activation energy for both forward and reverse reactions

41
Q

What does a catalyst do in a reaction?

A

It provides an alternative pathway of lower activation energy for both forward and reverse reactions

42
Q

The following equation represents the reaction between hydrogen gas and nitrogen gas. At what rate is NH3 forming when N2 reacts at a rate of 0.50 M min–1

N2(g) + 3H2(g) → 2NH3(g)

A
  1. look at moles
    1.0 M min^-1
43
Q

The factor that has the greatest effect on the increase in reaction rate when the temperature increases is that

a. the activation energy of the reaction increases.

b. the proportion of particles with high kinetic energy increases.

c. the activation energy of the reaction decreases.

d. the number of collisions between particles increases.

A

b. the proportion of particles with high kinetic energy increases.

43
Q

The factor that has the greatest effect on the increase in reaction rate when the temperature increases is that

a. the activation energy of the reaction increases.

b. the proportion of particles with high kinetic energy increases.

c. the activation energy of the reaction decreases.

d. the number of collisions between particles increases.

A

b. the proportion of particles with high kinetic energy increases.

43
Q

The factor that has the greatest effect on the increase in reaction rate when the temperature increases is that

a. the activation energy of the reaction increases.

b. the proportion of particles with high kinetic energy increases.

c. the activation energy of the reaction decreases.

d. the number of collisions between particles increases.

A

b. the proportion of particles with high kinetic energy increases.

44
Q

The factor that has the greatest effect on the increase in reaction rate when the temperature increases is that

a. the activation energy of the reaction increases.

b. the proportion of particles with high kinetic energy increases.

c. the activation energy of the reaction decreases.

d. the number of collisions between particles increases.

A

b. the proportion of particles with high kinetic energy increases.

Chem (3 decks)

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