Chem 280 midterm Ques ons and answers | updated
2026
Define Chemistry:
Science that tries to understand how ma er behaves by studying how atoms / molecules
behave
Scien fic Method / steps
A way of learning that emphasizes observa on/experimenta on to understand the world.
1. observa on
2. form hypothesis
3. test hypothesis by experiment
4. form law/theory
Observa ons
measurement of some aspect of nature
- some simple w/ naked eye, others rely on sensi ve instrumenta on
- occasionally observa on happens by chance
- usually involves measurement/descrip on of some aspect of physical world
Hypothesis
tenta ve interpreta on or explana on of observa on
-good hypothesis is falsifiable -> further tes ng has poten al to prove it wrong
Experiment
highly controlled observa ons designed to validate or invalidate hypothesis
- these results may confirm or show hypothesis to be wrong
- hypothesis may have to be modified or discarded/replaced
- leads to scien fic law
Scien fic Law
Brief statement that summarizes past observa ons and predicts future ones
The Law of Conserva on of Mass.
All ma er in chemical reac on is neither created nor destroyed
Theory
, one or more well-established hypothesis may for basis for scien fic theory
- theories provide broader/deeper explana on for observa ons + laws.
- they model nature + predict behavior that extends well beyond observa ons/laws on
which they are founded
- atomic theory: all ma er composed of small, indestruc ble par cles = atoms
What is the correct mul plier for the prefix cen ?
10-2
What is the correct scien fic nota on and total number of sig figs for 0.00032400?
3.2x10-4
The correct number of sig figs in the number 6.0220 is?
5
Determine the answer to the following mixed opera ons problem: (9.658 x 0.54) + 88.6 =
93.8
Determine the answer to the following mixed opera ons problem: (5.321 x 0.15) + 26.1 =
26.9
Determine the answer to the following mixed opera ons problem: (7.5 x 102 - 2.53 x 102) ÷
8.87 =
56
A silver bullet has a mass of 31.1 g and a density of 10.5 g/mL. What is the volume of the
bullet?
V=m/d
2.96mL
A metal object has a mass of 8.37 g. When it was placed in a graduated cylinder containing
20.0 mL of water, the water level rose to 23.1 mL. What is the density of the metal object?
d=m/v
2.7g/mL
Fahrenheit to Kelvin
Need celsius first
C = F - 32
-----------
1.8
2026
Define Chemistry:
Science that tries to understand how ma er behaves by studying how atoms / molecules
behave
Scien fic Method / steps
A way of learning that emphasizes observa on/experimenta on to understand the world.
1. observa on
2. form hypothesis
3. test hypothesis by experiment
4. form law/theory
Observa ons
measurement of some aspect of nature
- some simple w/ naked eye, others rely on sensi ve instrumenta on
- occasionally observa on happens by chance
- usually involves measurement/descrip on of some aspect of physical world
Hypothesis
tenta ve interpreta on or explana on of observa on
-good hypothesis is falsifiable -> further tes ng has poten al to prove it wrong
Experiment
highly controlled observa ons designed to validate or invalidate hypothesis
- these results may confirm or show hypothesis to be wrong
- hypothesis may have to be modified or discarded/replaced
- leads to scien fic law
Scien fic Law
Brief statement that summarizes past observa ons and predicts future ones
The Law of Conserva on of Mass.
All ma er in chemical reac on is neither created nor destroyed
Theory
, one or more well-established hypothesis may for basis for scien fic theory
- theories provide broader/deeper explana on for observa ons + laws.
- they model nature + predict behavior that extends well beyond observa ons/laws on
which they are founded
- atomic theory: all ma er composed of small, indestruc ble par cles = atoms
What is the correct mul plier for the prefix cen ?
10-2
What is the correct scien fic nota on and total number of sig figs for 0.00032400?
3.2x10-4
The correct number of sig figs in the number 6.0220 is?
5
Determine the answer to the following mixed opera ons problem: (9.658 x 0.54) + 88.6 =
93.8
Determine the answer to the following mixed opera ons problem: (5.321 x 0.15) + 26.1 =
26.9
Determine the answer to the following mixed opera ons problem: (7.5 x 102 - 2.53 x 102) ÷
8.87 =
56
A silver bullet has a mass of 31.1 g and a density of 10.5 g/mL. What is the volume of the
bullet?
V=m/d
2.96mL
A metal object has a mass of 8.37 g. When it was placed in a graduated cylinder containing
20.0 mL of water, the water level rose to 23.1 mL. What is the density of the metal object?
d=m/v
2.7g/mL
Fahrenheit to Kelvin
Need celsius first
C = F - 32
-----------
1.8
