Elements +
Compounds
Compounds
A pure substance can be classified as either compound or an
Element
Salt water is classified as a/an
homogeneous mixture
Express the number 215.0 in proper scientific notation with the correct number of significant figures.
2.150 x 102
Where in reference table can we find the formulas and equations for calculations?
Table T or page 12
A gas changes directly to a solid during which phase change
deposition
A substance in which the elements are chemically combined in a fixed proportion is a/an
Compound
Powdered sulfur is yellow, and powdered iron is gray. What will happen to these properties if these powders will be mixed?
These properties will not change/ they will remain the same.
What is the number 8.90 x 10-4 expressed in conventional form with the proper number of significant digits?
0.000890
An aluminum sample has a mass of 80.01 g and a density of 2.70 g/cm3 . Calculate the volume of aluminum in this sample.
29.6 cm3
Write the equation that represents sublimation?
Solid to Gas
Why is water classified as a compound?
Water can be broken down by chemical means.
Which procedure can be used to separate a mixture of ethanol and water?
distillation
Solve the problem below and express the answer in correct number of significant figures
52.6 x 1.214
63.9
At STP, which physical property of aluminum always remains the same from sample to sample?
Density
Which phase change reaction can be used to separate mixture of salt water?
Evaporation
Which substance cannot be broken down by chemical change?
an element
A mixture of sand and table salt can be separated by filtration because the substances in the mixture differ in
solubility in water
What is the number 2.1 x 103 expressed in a conventional form with the proper number of significant digits?
2,100
The accepted value for the percent by mass of water in a hydrate is 36.0%. In a laboratory activity, A student determined the percent by mass of water in the hydrate to be 37.8%. What is the percent error for the student's measured value?
5.0%
When Glucose is oxidized to produce Water and Carbon dioxide, what type of change had occurred?
chemical change
Which substance can be broken down by chemical change, but not by physical change?
A compound
Explain why the atmosphere is classified as a mixture.
It is made of various elements and compounds that are not chemically combined with each other.
An aluminum sample has a mass of 80.01 g and a density of 2.70 g/cm3 . According to the data, to what number of significant figures should the calculated volume of the aluminum sample be expressed?
3 significant figures.
To determine the density of an irregularly shaped object, a student immersed the object in 21.2 ml of water in graduated cylinder, causing the level of the water to rise to 27.8 ml. If the object had a mass of 22.4 grams, what was the density of the object?
3.4 g/ml
Describe the arrangements of particles in each of the phases of matter.
Solid - particles are tightly packed
Liquid - particles are slightly spaced
Gas - particles are moving in random motion