Chem Lab 1307

Pray to god brodie

The major component of Nature gas is:

A) Carbon dioxide

B) Methane

C) Oxygen

D) Nitrogen

B) Methane

Name ternary acid H₂SO₄

A) Sulfuric acid

B) Sulfurious acid

C) Carbonic acid

A) Sulfuric acid

Formula od sodium hydrogen carbonate is:

A)Na₂SO₄

B)NaHCO₃

C)Na₂CO₃

B)NaHCO₃

Reading the menisucs of following graduated cylinder, the volume is

A) 76.0 mL

B) 64.0 mL

C) 66.0 mL

D) 50.0 mL

B) 64.0 mL

The volume is 13.6g of gold is .706 cm³. What’s density of gold?

A) 9.6 g/cm³
B) 0.052 g/cm
C) 0.104 g/cm³
D) 19.3 g/cm³

D) 19.3 g/cm³

The reasons for using cruible tongs to handle the crucible and lid after their initial firing are to avoid contaminating the crucible and lid with the contaminants on the skin of the fingers and avoid burning the fingers

True

False

True

Why is it best to cool the crucible and lid (and sample) in a desicator rather than on the laboratory bench?

A) To minimize the probability of water being adsorbed onto the crucible and lid, as the hot crucinle and lid cool moisture from the atmosphere tends to condense on the surfaces.
B) To avoid the burning of the laboratory bench
C) To cool it fast
D) To keep the temperature at high level

A) To minimize the probability of water being adsorbed onto the crucible and lid, as the hot crucinle and lid cool moisture from the atmosphere tends to condense on the surfaces.

What need to do with the Mg ribbon before the combination reaction?

A) To be heated up
B) To be polished
C) To be washed with water
D) To be react with acid

B) To be polished

The molar mass of FeSO4 is 151.908 g/mol, given 1.2 mol of FeSO4, how many grams it is?

A) 182.3 g
B) 126.59 g
C) 201.2 g
D) 133.2 g

A) 182.3 g

A sample of table salt shows that 8.25 g of sodium and 12.75 g of chlorine are present. Calculate the moles of each element (hint: molar mas of Na 22.99; Cl 35.45) and please write the empirical formula of table salt

A) NaCl
B) NaCl2
C) Na2Cl
D) NaCl3

A) NaCl

2 moles of silver (Ag) metal completely reacts with 1 mole of sulfur (S0 to get silver sulfide. What is the empirical formula of silver sulfide.

A) AgS
B) Ag2S
C) AgS2
D) Ag3S

B) Ag2S

The reaction of A + B = AxBy is: ______ Reaction.

A) Combination Reaction
B) Decomposition Reaction
C) Redox Reaction
D) Displacement Reaction

A) Combination Reaction

What is the limiting reactant?

A) The product that you can make the most of
B) The reactant that determines how much product can be made
C) The reactant that is in excess
D) The amount of reactants that react with each other

B) The reactant that determines how much product can be made

Which of the following statement is correct?

A) A chemical reaction stops when the excess reactant is used up
B) A chemical reaction stops when the limiting reactant is used up
C) A chemical reaction stops when the temperature reaches the highest point
D) A chemical reaction stops when the time is up

B) A chemical reaction stops when the limiting reactant is used up

How many moles of Mg are needed to react completely with 12 mol of HCl?

Mg + 2HCL —> MgCl2+H2

A) 2 moles
B) 3 moles
C) 6 moles
D) 12 moles

C) 6 moles

Give a mixture gas of 2.2 mole of H2 and 0.8 mole of O2, the two gases will react with each other (See following equation). In this reaction, which gas is the limiting reagent?

2H₂(g) + O₂(g) —> 2H₂O(g)

A) O₂
B) H₂
C) H₂O

A) O₂

Given the reaction: 2H₂ + O₂ —> 2H₂O

In the experiment, there are 2 moles of H₂ reacted with excess amount of oxygen, 30g of H₂O generated. Please calculate the yield percentage.

A) 83.3%
B) 120%
C) 36g
D) 2 mol

A) 83.3%

What is the purpose of graviry filration?

A) To mix two reactants
B) To make the reactions throughly
C) To separate two liquids
D) To separate precipitate from liquid solution

D) To separate precipitate from liquid solution

For the reaction expressed by the equation, 6 Li(s) + N₂(g) —> 2 Li₃N(s), if 3 mol of Li(s) mixed with 1 mol of N₂(g), how many ____ mol of Li₃N(s) yielded?

A) 2 mol
B) 1 mol
C) 0.5 mol
D) 4 mol

B) 1 mol

The color of the copper (II) ion in solution is

A) Brown
B) Sky blue
C) Black
D) Pink

B) Sky blue

Write a balanced equation for the displacement of copper (II) ion from solution with magnesium metal.

Cu²⁺(aq) + Mg(s) —>

A) Cu²⁺(s) +Mg(aq)
B) Cu(s) + Mg²⁺(aq)
C) Cu(s) + Mg(s)
D) Cu(aq) + Mg(aq)

B) Cu(s) + Mg²⁺(aq)

What’s reaction type of the following?

2NaOH(aq) + Cu(NO₃)₂(aq) —> Cu(OH)₂(s) + 2NaNO₃(aq)

A) Single displacement
B) Double displacement
C) Redox
D) Oxidation

B) Double displacement

What is the purpose for centrifuge?

A) Let the two substances react completely
B) Separate the two substances
C) Mix the two substances
D) For fun

B) Separate the two substances

A 0.0152g sample of copper metal is recyceled through the series of reactions. At the end, 0.0076g copper is recoverd. What is the percent recovery of the copper metal?

A) 30%
B) 50%
C) 70%
D) 90%

B) 50%

Identify the ions present in a mixture of K₂CO₃ and FeCl₃ before any reaction occurs.

A) K⁺, CO₃^2-, Fe³⁺, Cl^-
B) K⁺, CO₃^-, Fe²⁺, Cl^-
C) K⁺, C²⁺, O^2-, Fe³⁺, Cl^-
D) K⁺, CO₃^2-, Fe^3-, Cl⁺

A) K⁺, CO₃^2-, Fe³⁺, Cl^-

Based on Law of Conservation of Mass:

When you burn a candle, all the remains is a small puddle of wax. The puddle of wax has less mess than the original candle. The rest of the original candle's mass was:

A) Destroyed
B) Changed to gases
C) Measured incorrectly
D) None of the above

B) Changed to gases

What type this reaction is: 4Si + S₈ —> 2Si₂S₄

A) Combination
B) Decomposition
C) Single Displacement
D) Double Displacement

A) Combination

“Spectator ions” appear in the total ionic equation for a reaction, but not in the net ionic equation.

True

False

True

Oxygen is a common oxidizing agent. If oxygen is an oxidizing agent in the reaction, the oxidation number of oxygen must be _____.

A) Increased
B) Decreased
C) No Change

A) Increased

In the following equation, select two correct statements regarding the reaction.

Zn(s) + Fe²⁺ —-> Zn²⁺ + Fe(s)

A) Oxidizing agent is Zn
B) Oxidinzing agent is Fe²⁺
C) Reducing agent is Zn
D) Reduction agent is Fe²⁺

B) Oxidizing agent is Fe²⁺

C) Reducing agent is Zn

Which of the following reactions is Redox Reaction?

A) HCl(aq) + NaOH(aq) —> NaCl(aq) +H₂O 
B) AgNO₃(aq) + NaCl(aq) —> NaNO₃(aq) + AgCl(s)
C) Mg(s) + CuCl₂(aq) —> MgCl₂(aq) + Cu(s)
D) H₃PO₄(aq) + 3NH₄OH(aq) —> (NH₄)₃PO₄ (aq) + 3H₂O

C) Mg(s) + CuCl₂(aq) —> MgCl₂(aq) + Cu(s)

Label the chemical change as an oxidation or a reduction process.

Mg(s) —> Mg²⁺ + 2e^-

A) Oxidation
B) Reduction

A) Oxidation