Chemistry Semester 2 Midterm (3/28/2024)

Instrukcije

Answer each of the following question according to the directions. For the drag and drop questions, answer choices may be reused in the same question.

1

Identify the compound with ionic bonds.

KBr

O₂

Ne

CO

1

To balance an equation ______________ must be placed in front of the compound(s) and or element(s).

subscripts

species

coefficients

reactants

1

Identify the compound with covalent bonds.

NaCl

CH₄

Mg

Ne

1

Which of the following contains BOTH ionic and covalent bonds?

CaSO₄

COS

SF₆

CaI₂

1

What is the charge on the Cr ions in Cr₂O₃?

2-

3+

2+

1+

1

Calculate the molar mass of Al(C₂H₃O₂)₃.

86.03 g/mol

56.00 g/mol

139.99 g/mol

204.13 g/mol

1

How many moles of N₂O₄ are in 76.3 g N₂O₄? The molar mass of N₂O₄ is 92.02 g/mol.

1.21 moles

0.829 moles

7.02 x 10³ moles

1.42 x 10^-4 moles

4

Drugi mogući odgovor:

233.99 g

6.02 x 10²³ atoms

1.10 x 10²⁴ atoms

9 mol

4

Drugi mogući odgovor:

1

3

2

4

1

When methane (CH₄) gas is burned in the presence of oxygen, the following chemical reaction occurs.
CH₄ + 2O₂ → CO₂ + 2H₂O
If 1 mole of methane reacts with 2 moles of oxygen, then

6.02 x 10²³ molecules of CO2 and 1.2 x 10²⁴ molecules of H2O are produced

1.2 x 10²⁴ molecules of CO2 and 1.2 x 10²⁴ molecules of H2O are produced

6.02 x 10²³ molecules of CO2 and 6.02 x 10²³ molecules of H2O are produced

1.2 x 10²⁴ molecules of CO2 and 6.02 x 10²³molecules of H2O are produced

1

A balanced chemical equation reflects the idea that the mass of the products

is less than the mass of the reactants

is not related to the mass of the reactants

equals the mass of the reactants

is greater than the mass of the reactants

1

A student heated a 10 g sample of a compound in an open container. A chemical reaction occurred. The mass of the sample was measured again and found to be less than before. Which of the following explains the change in mass of the sample?

Some of the lighter atoms were converted to energy.

One of the reaction products was a gas.

The reaction gave off more heat than was added.

The heat caused the compound to become less dense.

6

Drugi mogući odgovor:

80 g

128 g

98 g

157 g

1

The equation below represents a balanced chemical reaction:
2Mg(s) + O₂(g) --> 2MgO(s)
How many moles of MgO are produced when 7.2 moles of O₂react with excess Mg?

3.6 moles

14 moles

29 moles

22 moles

1

What type of force holds ions together in salts such as CaF₂?

gravitational

nuclear

electrostatic

magnetic

1

Which of the following pairs of atoms is unlikely to form a compound?

potassium (K) and iodine (I)

iron (Fe) and sulfur (S)

neon (Ne) and argon (Ar)

calcium (Ca) and chlorine (Cl)

1

Use the diagram to answer the following question.
How many bonds are made by each carbon atom in the molecule shown above?

three

four

two

one

1

Two elements in a molecule have the same electronegativity values. Which of the following most likely holds the elements together and why?

an intermolecular force, because the elements do not form a chemical bond

an ionic bond, because electrons transfer from one element to the other

a nonpolar covalent bond, because the elements share electrons equally

a polar covalent bond, because the elements do not share electrons equally

1

Which of the following are most directly involved in chemical bonding?

protons

neutrons

alpha particles

valence electrons

11

	Ionic Bond	Covalent Bond	Metallic Bond
Higher melting point
Lower melting point
Brittle and hard
Exists as solid, liquid, and gas at STP
Malleable and lustrous
Conductive as a solid
Poor conductor
Lattice made of positive and negative ions
Lattice of positive ions surrounded by sea of electrons
Shared electrons between two or more atoms

4

Drugi mogući odgovor:

5

8

6

1

6

For the reactions below, select the correct reaction type and drag it onto the equation.

Single Replacement
Double Replacement
Synthesis
Combustion
Decomposition

C₂H₄ + 3O₂ --> 2CO₂ + 2H₂O

6

Place the items in order to show how to solve a grams to mole stoichiometry problem.

Write a balanced equation
Identify the mole ratios of the balanced equation
Identify the given and unknown substances
Multiply by the mole ratio
Convert to moles by dividing by molar mass
Calculate the molar mass of the given

Chemistry Semester 2 Midterm (3/28/2024)

Identify the compound with ionic bonds.

To balance an equation ______________ must be placed in front of the compound(s) and or element(s).

Identify the compound with covalent bonds.

Which of the following contains BOTH ionic and covalent bonds?

What is the charge on the Cr ions in Cr2O3?

Calculate the molar mass of Al(C2H3O2)3.

How many moles of N2O4 are in 76.3 g N2O4? The molar mass of N2O4 is 92.02 g/mol.

When methane (CH4) gas is burned in the presence of oxygen, the following chemical reaction occurs. CH4 + 2O2 → CO2 + 2H2OIf 1 mole of methane reacts with 2 moles of oxygen, then

A balanced chemical equation reflects the idea that the mass of the products

A student heated a 10 g sample of a compound in an open container. A chemical reaction occurred. The mass of the sample was measured again and found to be less than before. Which of the following explains the change in mass of the sample?

The equation below represents a balanced chemical reaction: 2Mg(s) + O2(g) --> 2MgO(s)How many moles of MgO are produced when 7.2 moles of O2 react with excess Mg?

What type of force holds ions together in salts such as CaF2?

Which of the following pairs of atoms is unlikely to form a compound?

Use the diagram to answer the following question.How many bonds are made by each carbon atom in the molecule shown above?

Two elements in a molecule have the same electronegativity values. Which of the following most likely holds the elements together and why?

Which of the following are most directly involved in chemical bonding?

For the reactions below, select the correct reaction type and drag it onto the equation.

Place the items in order to show how to solve a grams to mole stoichiometry problem.

Identify the compound with ionic bonds.

To balance an equation ______________ must be placed in front of the compound(s) and or element(s).

Identify the compound with covalent bonds.

Which of the following contains BOTH ionic and covalent bonds?

What is the charge on the Cr ions in Cr2O3?

Calculate the molar mass of Al(C2H3O2)3.

How many moles of N2O4 are in 76.3 g N2O4? The molar mass of N2O4 is 92.02 g/mol.

When methane (CH4) gas is burned in the presence of oxygen, the following chemical reaction occurs. CH4 + 2O2 → CO2 + 2H2OIf 1 mole of methane reacts with 2 moles of oxygen, then

A balanced chemical equation reflects the idea that the mass of the products

A student heated a 10 g sample of a compound in an open container. A chemical reaction occurred. The mass of the sample was measured again and found to be less than before. Which of the following explains the change in mass of the sample?

The equation below represents a balanced chemical reaction: 2Mg(s) + O2(g) --> 2MgO(s)How many moles of MgO are produced when 7.2 moles of O2 react with excess Mg?

What type of force holds ions together in salts such as CaF2?

Which of the following pairs of atoms is unlikely to form a compound?

Use the diagram to answer the following question.How many bonds are made by each carbon atom in the molecule shown above?

Two elements in a molecule have the same electronegativity values. Which of the following most likely holds the elements together and why?

Which of the following are most directly involved in chemical bonding?

For the reactions below, select the correct reaction type and drag it onto the equation.

Place the items in order to show how to solve a grams to mole stoichiometry problem.

What is the charge on the Cr ions in Cr₂O₃?

Calculate the molar mass of Al(C₂H₃O₂)₃.

How many moles of N₂O₄ are in 76.3 g N₂O₄? The molar mass of N₂O₄ is 92.02 g/mol.

When methane (CH₄) gas is burned in the presence of oxygen, the following chemical reaction occurs.
CH₄ + 2O₂ → CO₂ + 2H₂O
If 1 mole of methane reacts with 2 moles of oxygen, then

The equation below represents a balanced chemical reaction:
2Mg(s) + O₂(g) --> 2MgO(s)
How many moles of MgO are produced when 7.2 moles of O₂react with excess Mg?

What type of force holds ions together in salts such as CaF₂?

Use the diagram to answer the following question.
How many bonds are made by each carbon atom in the molecule shown above?

What is the charge on the Cr ions in Cr₂O₃?

Calculate the molar mass of Al(C₂H₃O₂)₃.

How many moles of N₂O₄ are in 76.3 g N₂O₄? The molar mass of N₂O₄ is 92.02 g/mol.

When methane (CH₄) gas is burned in the presence of oxygen, the following chemical reaction occurs.
CH₄ + 2O₂ → CO₂ + 2H₂O
If 1 mole of methane reacts with 2 moles of oxygen, then

The equation below represents a balanced chemical reaction:
2Mg(s) + O₂(g) --> 2MgO(s)
How many moles of MgO are produced when 7.2 moles of O₂react with excess Mg?

What type of force holds ions together in salts such as CaF₂?

Use the diagram to answer the following question.
How many bonds are made by each carbon atom in the molecule shown above?