Fall Semester Science Review

Which Element is found in all three of these compounds?

C2H6 NaHCO3 C6H12O6 CO2

• Oxygen

• Sodium

• Hydrogen

• Carbon

The Table Shows the Chemical formulas for four substances.

Sub. 1 C2H6O

Sub. 2 C8H18

Sub. 3 CH3CH2Br

Sub. 4 C4H10O

Which substance have the same number of carbon atoms?

• Substance 1 and 2

• Substance 2,3, and 4

• Substance 2 and 3

• Substance 1 and 3

Sodium sulfate is used in laundry detergent. It is a compound that contains 2 atoms of sodium, 1 atom of sulfur, and 4 atoms of oxygen. What is the correct formula for sodium Sulfate?

• NA2SO4

• NA2S2O4

• Na2SO4

• Na2SO8

How many atoms of oxygen are found in aluminum nitrate, Al(NO3)3

• 3

• 6

• 7

• 9

The chemical formula below identifies an acid:

H3PO4

How many total atoms are represented in the chemical formula above?

• 3

• 8

• 9

• 4

A scientist spilled a few drops of diluted hydroelectric acid (HCI) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaHCO3) onto the spill. Which observation would provide the best evidence that a chemical reaction occurred?

• The baking soda and hydroelectric acid combined, and bubbles formed.

• The baking soda absorbed the hydroelectric acid.

• Some of the baking soda dissolved in the hydroelectric acid.

• The hydroelectric acid evaporated, leaving only the baking soda.

During an investigation, a student combined the two clear, colorless solutions below.

Solution 1: Compound A dissolved in water at 25 C

Solution 2: Compound B dissolved in water at 25 C

The student observed that the temperature changed from 25 C to 23 C when the solutions were combined and that a white substance rapidly formed and settled at the bottom of the container. What most likely happen to produce these results?

• One of the original compounds came out of solution.

• The solutions reacted chemically.

• Some of the water froze into ice crystals.

• Rapid evaporation of water occurred, leaving a solid.

Tomika added vinegar to a beaker containing a few chips of limestone. How could you tell a chemical change would be occurring in the beaker?

• The vinegar is evaporating

• The temperature remains the same

• The limestone is melting

• A gas is being produced

Which of the following represents a chemical reaction?

• a sugar cube dissolving in water

• a cake baking in an oven

• ice cubes forming in a freezer

• ice cream melting in a bowl

Which best would complete the the middle of this graphic organizer? Gas Produced, Color Change, Precipitate Produced, Temperature Change.

• Physical properties of elements

• Chemical properties of elements

• Evidence of physical change

• Evidence of a chemical reaction