Colegio San PatricioChemistry 9th grade

Name______________________________________________ Date _________________

1.- The following are chemical changes except:a) burning coal b) cutting a piece of breadc) explosion of fireworks d) digestion of food

2.- Which of the following is NOT a clue that a chemical reaction is taking place?a) a substance dissolves b) a change in colorc) a precipitate forms d) bubbles form

3.- The new substances produced in a chemical reaction have:a) the same properties as the original substancesb) different physical properties from the originalc) different chemical properties from the originald) different physical and chemical properties from the original

4.- A chemical reaction is:a) the rearrangement of atomsb) the breaking of bonds and the formation of new bondsc) process that changes the identify of a substanced) all are correct

Answer the following questions

5.- What evidence shows that the following are chemical reactions?

7.-

a) a yellow liquid is mixed with a colorless liquid and a yellow precipitate is formed at the bottom of the container

b) a red solid is placed in sunlight and after a period of time in becomes an opaque, orange solid

c) a silver metal when lit, reacts with oxygen in the air and produces light and heat.

Classify the following chemical reactions

NaHCO3 Na2CO3 + H2O + CO2 _______________________________

C8H18 + O2 CO2 + H2O _______________________________

AgNO3 + CaCl2 AgCl + Ca(NO3)2 __________________________________________________

Mg + HCl MgCl2 + H2 __________________________________________________

NO + O2 NO2 _________________________________________________