chem reactions 2

Which example provides evidence of a chemical change?

• Wood releases ash and smoke when burned.

• Rock particles separate when soil is being sifted.

• Boiling water bubbles when being heated.

• Sugar is not visible when dissolved in water.

The substances formed in a chemical reaction are known as......?

• products

• reactants

• solutions

• solutes

Which of the following is an example of a physical change that might increase or decrease the temperature, but does not involve a chemical change?

• mixing paint

• boiling water

• recrystallization

• evaporation

A precipitate is...

• a solid that falls out of a liquid solution
• a reactant in a reaction
• a clear substance
• the mass of a product

The left side of a chemical equation is known as the _______

• Reactants

• Products

The change of a substance into a completely new substance

• catalyst

• chemical change

• physical change

• surface area

This is the big number before substances that tell you how many of that substance there is

• coefficient

• subscript

• reactant

• product

During a chemical reaction-- is matter destroyed? 

• No, matter can never be destroyed-- it only moves
• Yes.  Matter is destroyed every day. 
• Depends on the type of chemical reaction. 
• You are a magician, sir. 

Four students performed four different investigations by combining different substances. Which of the observations is most indicative of a chemical reaction?

• investigation 1
• investigation 2
• investigation 3
• investigation 4

Which of the following is an example that includes evidence of a chemical reaction?

• A sample of zinc is placed in water and it settles to the bottom
• A solid block of ice is heated and it completely melts into a liquid. 
• Sugar that is burned gives off an odor and turns brown and then black.
• A tomato is placed into a blender and chopped up into smaller pieces.