Chem

Chem. 10

Test 1

I. Answer briefly.

1. Identify the following as A) physical property B) chemical property C) physical

change or D) chemical change

_____density

_____evaporation

_____the rusting of iron

_____viscosity

_____Ca metal burning in air

_____decantation

2. Classify the following as A) pure substance or B) mixture

_____beer

_____sugar

_____carbon

_____air

_____sea water

3. Give the name or symbol as appropriate

_____mercury

_____Sb

_____Au

_____Radon

_____silver

4. Four ways of separating the components of mixtures from each other are A) filtration B) evaporation C) decantation D) distillation. Which of these may best be used for each of the following mixtures? (Use letters)

_____salt in water

_____SiO₂ in water

_____alcohol in water

_____mud particles suspended in water

5. Below are listed some of the properties of the element sodium. Classify each of them as A) physical or B) chemical (Use letters)

____A grayish-white solid

____Forms sodium oxide when in contact with air

____Soft enough as to be cut with a knife

____Lighter than gold

____Reacts with cold water with explosive violence forming hydrogen gas

6. Write T if the statement is true; F if false.

___Each measured number has some uncertainty in it.

___There are 12 inches in 1 foot. Each of these numbers is exact.

___The number 0.008050 miles has 7 significant figures.

___To identify an element, we need only to know its mass number.

___There are 8 neutrons in an atom of carbon-14.

7. Classify the following elements as A)metal B) nonmetal or C) metalloid.

___phosphorus

___chlorine

___silicon

___lead

___calcium

8. In no more than 2 sentences each, state the briefly the most significant

contribution of each of the following to our knowledge of atomic structure.

John Dalton

J.J. Thomson

Ernest Rutherford

Dmitri Mendeleev

9. Write a brief comparison of the following:

organic vs. inorganic compounds

ionic vs. molecular compounds

a period vs. a family of elements

a main group of elements vs. transition -metal group of elements

II. Problems

Show the complete solution, with units to earn any kind of credit. Express the answer to the proper number of significant digits. Answers only, without the solution will not be graded.

In a new measuring system devised by an unknown scientist, 5.06 foc = 1.05 dou

and 2.71 dou = 3.00 lam. How many foc is equivalent to 10.00 lam?

Change 87.5^oF to Celsius.

What is the mass in grams of 25.0 mL of oil whose density is 0.843 g/mL?

An element has 2 isotopes. Isotope A has an atomic mass of 10.01294 amu and a % abundance of 19.6%. If the atomic mass of isotope B is 11.00931 amu, determine the average atomic mass of this element.

A kilowatt-hour (kWh) is a unit of energy equal to 3.6 x 10⁶ J. An electric bill

lists the energy consumed as 200. kWh. Change this to a) J and b) to calories.

6. A graduated cylinder holds 30.5 mL of water. A solid weighing 22.861 g is

dropped in the water. If the water level rises to the 41.6 mL mark, what is

the density of the object in g/mL?