Unit Conversions
If a building is 174 m tall, what is its height in feet (1 m= 3.28 ft)
570.72 ft
What is a pure substance?
A substance of constant composition.
What is a mixture?
A combination of two or more substances that are not chemically combined.
True or false: filter paper can be used to separate salt from water?
False.
What are the two branches of physical science?
Chemistry and physics.
If the length of a wall is 48.75 ft, what is its length in centimeters (1 ft = 12 in; 1 in = 2.54 cm)?
1,485.9 cm
What is an element? Give two examples of an element.
A pure substance that cannot be broken down into smaller pieces. Examples: O, N, C, Pb, U (anything that is found on the periodic table).
Give one example of a homogenous mixture and one example of a heterogenous mixture.
Homogenous: salt water, metal alloys, sugar water...
Heterogenous: sand, soil, salad dressing...
Explain how to separate sand from water. What is this separation method called?
Pour the water and sand mixture through filter paper. The sand stays in the filter and the water goes through. This is called filtration.
What is matter?
Anything that takes up space.
Convert 7,045 pm into nm (1 nm= 1,000 pm)
7.045 nm
Is Na an element or a compound?
Element.
What is the difference between a heterogenous and homogenous mixture?
In a homogenous mixture, particles are uniformly distributed while they are not uniformly distributed in a heterogenous mixture.
What separation method was used to separate ink pigments?
Chromatography
Answers could include plastics, pesticides, fuels, fabrics, paper, fertilizer, rubber, drugs/ medicines, etc.
Conver 84,814 nm into mm (1,000 nm = 1 µm; 1,000 µm= 1 mm).
0.084814 mm.
What is a compound? Give two examples of a compound.
A compound is a pure substance made up of two or more elements (H2O, CH4, NaCl... any example of a compound would be accepted).
What is the difference between a colloid and a suspension?
Colloids have particles small enough that they do not settle, but large enough that they scatter light. Suspensions have large enough particles that they can settle out.
Give one example of how chromatography is used in the real world.
In forensics to separate ink pigments (ransom notes, counterfeit currency) or to detect drugs or alcohol in blood samples. (other examples could be checking air quality, pesticides in soil, etc.).
Is water an element or a compound? What evidence supports your answer?
Compound because it can be split up into two different elements (Hydrogen and Oxygen).
Convert 12 mm to pm. (1 mm= 1,000 µm; 1 µm = 1,000 nm; 1 nm= 1,000 pm).
12,000,000,000 (12 billion) pm.
Give an example of a pure substance that is both an element and a molecule.
O2, N2, O3...
What is the Tyndall Effect?
The scattering of light in a colloid.
Explain how you would separate a mixture of sand, salt and iron filings (you must use at least 3 separation methods).
First: magnet to separate iron filings.
Second: add water and pour through filter (sand stays in filter, water and salt go through).
Evaporation: boil water away to leave behind salt.
How is a mixture different than a compound?