Gen Chem Midterm 1 Review

Numbers and Math

100

In the number 4,912.3, what is the value of the digit in the tenths place?

0.3

200

Write 0.000710 in scientific notation

7.10 x 10^-4

300

Solve for x:

3x + 7 = 22

x = 5

400

What is 35% of 240?

84

500

Solve the system:

y = 2x + 1 and y = 3x - 4

x = 5, y = 11

Matter and Mixtures

100

Is salt water homogeneous or heterogeneous?

Homogeneous

200

Classify each as an element, compound, or mixture:

Air, O₂, and H₂O.

Air = mixture

O₂ = element

H₂O = compound

300

Rusting of iron is a chemical or physical change?

Chemical

400

A clear liquid boils at a single temperature and leaves no residue when evaporated. Is it pure or a mixture?

Pure - constant boiling point and no residue suggest a single substance

500

You have a gray solid that melts at one sharp temperature. It cannot be separated into simpler substances by physical means, but heating it strongly in air produces two different gases. Classify it as element, compound, or mixture and justify.

Compound - sharp melting point and not being able to be separated by physical means rules out mixture. While the heating strongly leading to two different gases points to compound. 

Energy and Heat

100

Convert 25 ^oC to Kelvin.

298.15 ^oC

200

How many Calories are in 10 g of carbohydrate? 

Carbs (4 kcal/g)

40 Cal

300

Which needs more heat to warm 1g by 1 ^oC: water (4.18 J/g^oC) or iron (0.452 J/g^oC)?

Using the formula for heat energy (q = mc\Delta T):

• Water: 1g x 4.18 J/g^oC x 1^oC = 4.18 J

• Iron: 1g x 0.452 J/g^oC x 1^oC = 0.452 J

Water requires nearly 10 times more heat energy to raise the temperature of 1 g by 1^oC due to its higher specific heat capacity. 

400

How much heat is needed to raise 20 g of water by 10^oC?

Q = mc delta T

Q = 20 g x 4.184 x 10 = 836.8 J 

500

On a heating curve, what happens to temperature during a phase change?

It stays constant (straight horizontal line)

Atoms and Isotopes

100

How many protons does a neutral carbon atom have?

6

200

How many neutrons are in ⁸⁰Br?

45

300

What is the charge of an electron?

-1

400

Two atoms with the same number of protons but different neutrons are called what?

isotopes

500

Calculate the atomic mass of an element with 80% abundance of mass 23 and 20% of mass 24?

23.2 amu

Electron Configuration

100

How many electrons fit in a p subshell?

6

200

How many valence electrons does sodium have?

1 

[Ne]3s¹

300

What is the electron configuration of copper?

1s²2s²2p⁶3s²3p⁶3d¹⁰4s¹

[Ar]3d¹⁰4s¹

400

How many unpaired electrons does carbon have in its ground state?

2

500

Which orbital shape has four lobes?

d orbital