Liora Fiksel
BULGRIN Integrated Physical Science
a) Go to www.chemthink.com. Log in using your user name and password. (If you forgot, you need to WAIT
QUIETLY until your teacher is done introducing the lesson)
b) Scroll to C H E M I C A L R E A C T I O NS then the tutorial under the Chemical Reactions menu.
c) Complete the tutorial. As you complete the tutorial, write down the answers to the questions below.
d) Once you have successfully completed the tutorial and this worksheet, complete the Q uestion Set.
C H E M I C A L R E A C T I O NS T U T O R I A L Q U EST I O NS :
1. Starting materials in a chemical reaction are called reactants.
2. The ending materials in a chemical reaction are called products.
3. The arrow indicates a chemical change has taken place.
4. All reactions have one thing in common: there is a rearragngement of bonds.
5. Chemical reactions always involve breaking bonds, forming bonds, or both.
6. In all reactions we still have all of the same atoms at the end that we had at the start.
7. In every reaction there can never be any atoms or new atoms missing when the reaction is over.
8. Chemical reactions only rearrange the bonds in the atoms that are already there.
9. Let’s represent a reaction on paper. For example, hydrogen gas (H2) reacts with oxygen gas (O2) to form water
(H2O):
H2 +O2=H2O
If we use only the atoms shown, we’d have 2 atoms of H and 3 of atoms of O as reactants. This would make water molecule of H2O, but we’d have 1 atom of O leftover. However this reaction only makes H2O.
Remember: reactions are not limited to 1 molecule each of reactants. We can use as many as we need to balancethe chemical equation.
A balanced chemical reaction shows:
a) What atoms are present before (in the reactants) and after (in the products)
b) How many of each reactant and product is present before and after.
10. So to make H2O from oxygen gas and hydrogen gas, the balanced equation would be:
__2__ H2+___O2=__2__H2O
Which is the same as:
11. This idea is called the conservation of mass.
12. There must be the same mass and the same number of atoms before the reaction in the reactants and after the reaction (in the products).
13. What is the balanced equation for this reaction?
__2__ Cu + _____ O2 __2__ CuO
14. In the unbalanced equation there are:
Reactants
Cu atoms _2____
O atoms _2____
Products
Cu atoms __2____
O atoms __2____
15. To balance this equation, we have to add _2_ molecules to the products, because this reaction doesn’t make
lone __2___ atoms.
16. When we added a molecule of CuO, now the number of __CU___ atoms is balanced but the number of _Oxygen___ atoms don’t match. Now we have to add more __CU___ atoms to the reactants.
17. The balanced equation for this reaction is
Cu+O2=2 CuO
This is the same thing as saying:
Reactants
# Cu atoms __2___ = # Cu atoms __2____
# O atoms ___2__ = # O atoms __2____
18. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
CH4+2O2=2H2O+CO2
19. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
N2+3 H2=2 NH3
20. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
2 KCIO3= 2 KCI+3 O2
21. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
4 Al+3 O2=2 Al2O3
SU M M A R Y
1) Chemical reactions always involve breaking bonds, forming bonds, or both.
2) The Law of Conservation of Mass says that the same atoms must be in the reactants and in the products.
3)To balance a chemical equation, you change the coefficients in front of each substance until there are the same number of each type of atom in both reactants and products
BULGRIN Integrated Physical Science
a) Go to www.chemthink.com. Log in using your user name and password. (If you forgot, you need to WAIT
QUIETLY until your teacher is done introducing the lesson)
b) Scroll to C H E M I C A L R E A C T I O NS then the tutorial under the Chemical Reactions menu.
c) Complete the tutorial. As you complete the tutorial, write down the answers to the questions below.
d) Once you have successfully completed the tutorial and this worksheet, complete the Q uestion Set.
C H E M I C A L R E A C T I O NS T U T O R I A L Q U EST I O NS :
1. Starting materials in a chemical reaction are called reactants.
2. The ending materials in a chemical reaction are called products.
3. The arrow indicates a chemical change has taken place.
4. All reactions have one thing in common: there is a rearragngement of bonds.
5. Chemical reactions always involve breaking bonds, forming bonds, or both.
6. In all reactions we still have all of the same atoms at the end that we had at the start.
7. In every reaction there can never be any atoms or new atoms missing when the reaction is over.
8. Chemical reactions only rearrange the bonds in the atoms that are already there.
9. Let’s represent a reaction on paper. For example, hydrogen gas (H2) reacts with oxygen gas (O2) to form water
(H2O):
H2 +O2=H2O
If we use only the atoms shown, we’d have 2 atoms of H and 3 of atoms of O as reactants. This would make water molecule of H2O, but we’d have 1 atom of O leftover. However this reaction only makes H2O.
Remember: reactions are not limited to 1 molecule each of reactants. We can use as many as we need to balancethe chemical equation.
A balanced chemical reaction shows:
a) What atoms are present before (in the reactants) and after (in the products)
b) How many of each reactant and product is present before and after.
10. So to make H2O from oxygen gas and hydrogen gas, the balanced equation would be:
__2__ H2+___O2=__2__H2O
Which is the same as:
| # of atoms in reactants | elements | # of atoms in products |
| 4 | H | 4 |
| 2 | O | 2 |
11. This idea is called the conservation of mass.
12. There must be the same mass and the same number of atoms before the reaction in the reactants and after the reaction (in the products).
13. What is the balanced equation for this reaction?
__2__ Cu + _____ O2 __2__ CuO
14. In the unbalanced equation there are:
Reactants
Cu atoms _2____
O atoms _2____
Products
Cu atoms __2____
O atoms __2____
15. To balance this equation, we have to add _2_ molecules to the products, because this reaction doesn’t make
lone __2___ atoms.
16. When we added a molecule of CuO, now the number of __CU___ atoms is balanced but the number of _Oxygen___ atoms don’t match. Now we have to add more __CU___ atoms to the reactants.
17. The balanced equation for this reaction is
Cu+O2=2 CuO
This is the same thing as saying:
Reactants
# Cu atoms __2___ = # Cu atoms __2____
# O atoms ___2__ = # O atoms __2____
18. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
CH4+2O2=2H2O+CO2
| # of atoms in reactants | Element | #of atoms in Products |
| 1 | C | 1 |
| 4 | H | 2 |
| 2 | O | 3 |
19. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
N2+3 H2=2 NH3
| # of atoms in reactants | Element | #of atoms in Products |
| 2 | N | 1 |
| 2 | H | 3 |
20. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
2 KCIO3= 2 KCI+3 O2
| # of atoms in reactants | Element | # of atoms in prodcts |
| 1 | K | 1 |
| 1 | CI | 1 |
| 3 | O | 2 |
21. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
4 Al+3 O2=2 Al2O3
| # of atoms in reactants | Element | # of atoms in products |
| 1 | Al | 2 |
| 2 | O | 3 |
SU M M A R Y
1) Chemical reactions always involve breaking bonds, forming bonds, or both.
2) The Law of Conservation of Mass says that the same atoms must be in the reactants and in the products.
3)To balance a chemical equation, you change the coefficients in front of each substance until there are the same number of each type of atom in both reactants and products
No comments:
Post a Comment