chemistry homework’s

Chem 104
NAME_________________________
Homework #7
Due Monday 24 October 2022
Atoms and Balanced Equations
This homework will use PhET Interactive Simulations to review atoms and subatomic
particles and practice balancing equations.
Part 1:
Load the Build an Atom simulation (https://phet.colorado.edu/sims/html/build-an-atom/latest/build-anatom_en.html)
Test your understanding: Play all four games and share your scores below.
_____
_____
______
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For the given element or ion symbol determine the number of protons, neutrons, and electrons.
Symbol
Protons (p+)
Neutrons (n0)
Si
Au
BrCa2+
Fe3+
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Chem 104 – Review
Electrons (e-)
Part 2:
Load the Balancing Chemical Equations simulation (https://phet.colorado.edu/sims/html/balancingchemical-equations/latest/balancing-chemical-equations_en.html)
1. Explore the Balancing Chemical Equations simulation.
a) What are the different ways that the simulation indicates when an equation is balanced?
2. For each balanced reaction, indicate the total number of molecules in the table below.
Reaction
Total Number of Molecules
Reactant Side
Product Side
(Left)
(Right)
Make Ammonia
Separate Water
Combust Methane
3. Is the number of total molecules on the left side of a balanced equation always equal to the number
of total molecules on the right side of the equation? Explain your answer.
4. For each balanced reaction, indicate the total number of atoms in the table below.
Reaction
Total Number of Atoms
Reactant Side
Product Side
(Left)
(Right)
Make Ammonia
Separate Water
Combust Methane
5. Is the number of total atoms on the left side of a balanced equation always equal to the number of
total atoms on the right side of the equation?
6. What is the same on the left and right side of a balanced equation? Explain your answer.
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Chem 104 – Review
7. Play all levels of the game and write down the balanced chemical equations as you solve them.
Level 1
A. _______________________________________________________________
B. _______________________________________________________________
C. _________________________________________________________________
D. ________________________________________________________________
E. ________________________________________________________________
Level 2
A. _______________________________________________________________
B. _______________________________________________________________
C. _________________________________________________________________
D. ________________________________________________________________
E. _______________________________________________________________
Level 3
A. _______________________________________________________________
B. _______________________________________________________________
C. _________________________________________________________________
D. ________________________________________________________________
E. ________________________________________________________________
8. In the simulation, were you able to use non-integer numbers (like ½ or 0.43) for the coefficients in a
balanced equation? Why do you think this is?
a) Which of the following are coefficients you could use in a balanced equation?
☐½
☐¾
☐1
☐2
☐6
☐9
b) If you were balancing an equation containing the O2 molecule, which of the following would be
correct representations of O2 and its coefficient?
☐ ½O2
☐ O2
☐ 3O2
☐ 6O2
☐ 3O
☐ 5O3
9. What do you have to do to the coefficients of equation I below to get to equation II?
i.
2 SnO2 + 4 H2  2 Sn + 4 H2O
ii.
SnO2 + 2 H2  Sn + 2 H2O
a) Both equation I and II are balanced, but equation I is the correct way to write the balanced
equation. True or False?
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Chem 104 – Review
BALANCE THE EQUATIONS BELOW.
A. ___ NaNO3 + ___ PbO  ___ Pb(NO3)2 + ___ Na2O
B. ___ Ca3P2 + ___ H2O  ___Ca(OH)2 + ___ PH3
C. ___Fe2O3 + ___ CO  ___Fe + ___ CO2
D. ___NH3 + ___ O2  ___ NO2 + ___ H2O
E. ___FeS + ___O2  ___Fe2O3 + ___SO2
F. ___ C3H6O2 + ___ O2  ___ CO2 + ___ H2O
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Chem 104 – Review
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Chem 104 – Review