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23 Cards in this Set

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  • Back

A student concludes that a chemical reaction performed in a classroom investigation was exothermic. To communicate the validity of this conclusion, which would make the best visual evidence in a presentation?



a. Photographs of reactants and products


b. Listing of masses of reactants and products


c. Listing of time from start to finish of reaction


d. Photograph of a flame produced when the chemicals reacted

d. Photograph of a flame produced when the chemicals reacted

Two chemicals react in a beaker that has water droplets on the outside of the bottom of the beaker. The water droplets freeze. Which statement best describes the reaction?



a. Endothermic because energy is absorbed


b. Endothermic because energy is released


c. Exothermic because energy is absorbed


d. Exothermic because energy is released

a. Endothermic because energy is absorbed

When coal burns, the reaction (releases/absorbs) heat and is (endothermic/exothermic)?

releases, exothermic

A hot pack is a product that releases hear when chemicals inside of it interact. What is taking place inside an active hot pack?



a. Electric current


b. a net loss of mass


c. thermal insulation


d. an exothermic reaction

d. an exothermic reaction

A student places a chemical in an insulated container and measures the temperature. A second chemical is added and the container is sealed and the temperature is monitored. What is the student trying to determine?



a. What color changes can be observed?


b. How much precipitate is formed?


c. Is hear absorbed or released?


d. How can this reaction be reversed?

c. Is hear absorbed or released?

Which reaction is endothermic?



cold pack


coal burning


striking a match


charcoal grill fire

cold pack

What information does the chemical equation 2C4H10+1302-->8CO2+10h2O provide?



a. How long the reaction takes to occur


b. The safest way to carry out the reaction


c. Whether the reaction is exothermic or endothermic


d. what kind of chemicals are produced by the reaction


d. what kind of chemicals are produced by the reaction


After Jimmy placed raw potato slices and hydrogen peroxide (H2O2) in a plastic bag, he concluded that an exothermic reaction had taken place. Which of the following supports Jimmy's conclusion?



a. the plastic bag got cooler


b. the plastic bag got warmer


c. the potatoes changed color


d. the hydrogen peroxide bubbled


b. the plastic bag got warmer


or


d. the hydrogen peroxide bubbled

Which statement supports that a chemical reaction took place?



a. changes in color


b. new substance was formed


c. physical change in iron occurred


d. original substances were present after

b. new substance was formed

which activity is an example of a chemical change?



a. sugar dissolving in water


b. water evaporating in air


c. lighting a match


d. freezing water

c. lighting a match

Anita heats a beaker containing water. As the temperature of the water increases, which change to the water molecules occur?



a. the molecules move at a faster rate


b. the molecules become more massive


c. the molecules expand and become wider


d. the molecules separate into atoms of hydrogen and oxygen

a. the molecules move at a faster rate

In which example is a chemical change taking place?



a. a piece of metal is cut in half


b. an ice cube melts on a counter


c. a camper roasts marshmallows over a burning fire


d. a baker mixes together flour and sugar to make dough

c. a camper roasts marshmallows over a burning fire

which observation should be listed as a chemical change?



a. substance was heated


b. shape of substance changed


c. volume of substance changed


d. substance changed into new substance

d. substance changed into new substance

Why are lighting a match and baking a cake considered chemical changes?



a. change state of matter


b. create new substances


c. change volume


d. create energy

b. create new substances

which best demonstrates a chemical change?



a. salt dissolving


b. wood burning


c. water boiling


d. ice melting

b. wood burning

which is an example of a chemical change?



a. sand separated from water by filtering


b. water evaporating from a puddle


c. a rock being eroded by wind


d. nail rusting in water

d. nail rusting in water

Chemical change in matter?



a. evaporation of water


b. grinding of a rock


c. melting of ice


d. rusting of iron

d. rusting of iron

example of a chemical change?



a. fog rising off a river


b. wood burning in a fireplace


c. ice cream melting in the sunshine


d. grinding peppercorn into pepper flakes

b. wood burning in a fireplace

chemical change that absorbs energy?

endothermic


chemical change that releases energy?

exothermic


which of these describes polypropylene?



a. ketone


b. monomer


c. alcohol


d. polymer

d. polymer

polymer is made up of repeating units of...

monomers

which is not a natural polymer?



a. hair


b. protein


c. plastic


d. rubber

d. rubber