UNIT 1 (Physical and Chemical Properties of Matter) HOMEWORK QUESTIONS
Write 57.0 in scientific notation.
5.7E1
Round to 3 significant figures: 57.048
57.0
Write 75.0 in scientific notation.
7.5E1
Write 0.00763 in scientific notation.
7.63E-3
Round to 3 significant figures: 0.0074983E4.
0.00750E4 or 75.0
Round to 3 significant figures: 0.0076321
0.00763
How many significant figures does 20miles have?
1
Write 12.2 in scientific notation.
1.22E1
Write 1760 in scientific notation.
1.760E3
Round to 3 significant figures: 12.17.
12.2
Round to 3 significant figures: 1764.9.
1760
How many significant figures does 0.0051g have?
2
How many significant figures does 0.010 have?
2
How many significant figures does 11m have?
2
How many significant figures does 22,000 have?
2
How many significant figures does 8.9E-2kg have?
2
How many significant figures does 0.00900L have?
3
How many significant figures does 90.4ºC have?
3
Sugar water is a (solid-solid/solid-liquid/gas-liquid/gas-gas).
solid-liquid
Carbon mixed with iron to form steel is a (solid-solid/solid-liquid/gas-liquid/gas-gas).
solid-solid
The term gas is limited to those substances that exist in the gaseous state at ordinary --- and ---.
temperatures, pressure
Gas (shape, volume, expansion, compressibility)
Indefinite, indefinite, great, great.
True/False: The properties of compounds are different from those of their component elements.
True (ex. carbon, hydrogen, and oxygen have totally different properties as a compound (sugar) than they do as individual elements)
What are some words that describe a physical change?
[Boil, freeze, melt, condense] reversible/[break, split, grind, cut, crush] irreversible.
How many phases exist in these types of mixtures? a. Homogenous b. Heterogenous
a. 1 b. 2 or more
Which of the following is NOT a state of matter? a. Water b. Gas c. Liquid d. Solid
a. Water
During a chemical reaction, the mass of products is always equal to the mass of ---.
reactants
In chemical reactants, the starting substances are called --- and the substances formed are called ---.
reactants, products
Which of the following is NOT a physical property? a. Odor b. Density c. Boiling point d. Corrosion
d. Corrosion
Can a compound be broken down to smaller components by physical means?
No, because they are chemically bound and must therefore be separated using chemical means.
Why are physical properties better used to separate mixtures than chemical properties?
Because it is easier and doesn't require an elaborate set-up.
What are some characteristics that indicate a chemical change is occurring?
Burn, corrode, rot.
Reversible Changes
Changes that result in a change of state.
What is a chemical property?
Characteristics of a material that become evident when that material undergoes a chemical change (ex. oxidation/rust, flammability).
Is adding HCl to Mg a physical or chemical change?
Chemical
Is burning paper a physical or chemical change?
Chemical
Write 98.5 in scientific notation.
9.85E1
Round to 3 significant figures: 98.473.
98.5
What happens in a chemical reaction?
A new substance is produced.
Accurate or precise: correct.
Accurate
Accurate or precise: single measurement.
Accurate
Accurate or precise: true value.
Accurate
Accurate or precise: 99 of 100 shots are made.
Accurate AND precise
What is used to represent each element?
Chemical symbol
Solid (shape, volume, expansion, compressibility)
Definite, definite, very slight, poor.
What are the two groups in which substances can be classified?
Element and compound
True/False: A heterogenous mixture is one that has a completely uniform composition.
False
True/False: All samples of a substance have different physical properties.
False
True/False: Elements can be separated easily into simpler substances.
False
True/False: It is always easy to separate the components in mixtures.
False
Liquid (shape, volume, expansion, compressibility)
Indefinite, definite, moderate, poor.
How can mixtures be separated?
Most use physical properties: boiling point differences, melting point differences, particle size, density, magnetism, solubility, color, smell (ex. separate aluminum and iron nail using magnetism).
Accurate or precise: 33 of 100 shots are made, rest miss.
Neither
Is dissolving NaCl a physical or chemical change?
Physical
Is grinding CuSo4 a physical or chemical change?
Physical
Is melting candle wax a physical or chemical change?
Physical
Is mixing NaCl and sand a physical or chemical change?
Physical
Is tearing Mg ribbon a physical or chemical change?
Physical
Is tearing paper a physical or chemical change?
Physical
Is heating CuSO4 a physical or chemical change?
Physical/Chemical
Accurate or precise: multiple measurements.
Precise
Accurate or precise: repeatable.
Precise
Accurate or precise: 99 of 100 shots hit the front of the rim, but bounce off.
Precise, but not accurate
Qualitative or quantitative observation: the flame is hot.
Qualitative
Qualitative or quantitative observation: a candle has a mass of 90g.
Quantitative
What is another name for a homogenous mixture?
Solution
What do boiling, melting, and freezing have in common?
They are all temperatures at which a change of state occurs and are all physical properties.
True/False: A chemist can help identify a substance by its physical properties.
True
True/False: Chemical properties are observed only when a substance undergoes a chemical change.
True
True/False: Most samples of matter are mixtures.
True
True/False: The elements that make-up a substance is always present in the same proportions.
True
True/False: The words gas and vapor can be used interchangeably.
True
Which of the following describes a part of a system with uniform composition and properties? a. Solution b. Mixture c. State d. Phase
d. Phase
Which of the following best completes this sentence?: A chemical change --- results in a change in chemical composition of the substances involved. a. Sometimes b. Rarely c. Always d. Never
c. Always
Compounds are substances that can be separated into simpler substances only by --- means.
chemical
A physical change alters a given material without changing its chemical ---.
composition
The subscript numbers in chemical formulas represent the proportions of the various elements in the ---.
compound
The law of conservation of mass states that in any physical change or chemical reaction, mass is neither --- nor ---.
created, destroyed.
Air is a (solid-solid/solid-liquid/gas-liquid/gas-gas).
gas-gas
Soda water is a (solid-solid/solid-liquid/gas-liquid/gas-gas).
gas-liquid