Chem 1100 Exam 1 - Mizzou Prof. Suits.

What is the best definition of a scientific hypothesis?

A tentative model that describes the underlying cause of observations and laws

To explain natural phenomena, scientists must...

Make observations

What contributions did alchemists of the Middle Ages make to modern science?

Metallurgy and the development of scientific techniques

The scientific revolution of the 1500s was makes by a move away from _____ and towards ______ as a method for explaining the natural world.

Reason; observation

Which of these substances are mixtures?

1. Steam

2. Crude Oil

3. Salt water

4. Gun Powder

5. Oxygen

6. Mercury

2, 3, 4

What is an example of a chemical change?

Wood burning

True or false: The Composition of mixtures if variable, and the composition of pure substances is fixed.

True

True or false: A chemical compound has a variable composition

False

Methane and oxygen react to form carbon dioxide and water. What is the mass of water formed if 3.2g of methane reacts with 12.8g of oxygen to produce 8.8g of carbon dioxide>

7.2 grams

True or false: All samples of a given compound have the same proportion of consistent elements, in regards to the law of constant composition.

True

How many significant figures are in the number 10,100

3

Determine the density of a 50.0g sample of mercury having a volume of 3.66 mL. Carry out the calculation to the correct number of significant digits.

13.66g/ML

What is the correct SI unit for time?

Seconds

Solve the problem: 1.5 x 10^3 + 3.14 x 10^4 - 1.21 x 10^2

3.28 x 10^4

True or false: 100ppm is the equivalent of 0.01%?

True

True or false: 6.00022 x 10^6 is the correct scientific notation for 6,000,220.

True

Refer to graph on practice test. According to the graph, what is the pH solution after 8mL of the base has been added?

pH of 4

True or false: Atoms are the smallest visible particles of an element.

False

True or false: K is the correct chemical symbol for potassium

True

Nonmetals tend to _____ electrons to form ________ ions.

gain; negative

When an oxygen atom gains two electrons, it becomes a _______ with a charge of ________.

Cation; 0

Elements belonging to the same group have the same __________.

number of valence electrons

Calculate the number of moles in a 233 gram sample of barium

1.70 moles. (233g/atomic mass of barium).