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Chem Equations Gizmo Virtual Assignment
General Chemistry I (CHEM 1110)
Pellissippi State Community College
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Name: ______________________________________ Date: ________________________
Student Exploration: Chemical Equations
Vocabulary: Avogadro’s number, chemical equation, chemical formula, chemical reaction, coefficient, combination, combustion, conservation of matter, decomposition, double replacement, molar mass, mole, molecular mass, molecule, product, reactant, single replacement, subscript
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
- A candle is placed on one pan of a balance, and an equal weight is placed on the other pan.
What would happen if you lit up the candle and waited for a while? ____________________
- Suppose the candle was placed in a large, sealed jar that allowed it to burn for several minutes before running out of oxygen. The candle and jar are balanced by an equal weight.
In this situation, what would happen if you lit up the candle and waited? ________________
Gizmo Warm-up Burning is an example of a chemical reaction. The law of conservation of matter states that no atoms are created or destroyed in a chemical reaction. Therefore, a balanced chemical equation will show the same number of each type of atom on each side of the equation.
To set up an equation in the Chemical Equations Gizmo, type the chemical formulas into the text boxes of the Gizmo. First, type in “H2+O2” in the Reactants box and “H2O” in the Products box. This represents the reaction of hydrogen and oxygen gas to form water.
- Check that the Visual display is chosen on each side of the Gizmo, and count the atoms.
A. How many hydrogen atoms are on the Reactants side? ____ Products side? ____
B. How many oxygen atoms are on the Reactants side? ____ Products side? ____
- Based on what you see, is this equation currently balanced? _________________________
Diane Glebus
The weight would go down.
It would stay equal.
2 2
2 1
No
Activity A:
Interpreting chemical formulas
Get the Gizmo ready: Erase the chemical formulas in each text box. Check that the Visual displays are selected.
Introduction: To balance a chemical equation, you first need to be able to count how many atoms of each element are on each side of the equation. In this activity, you will practice counting the atoms that are represented in chemical formulas.
Question: How do we read chemical formulas?
- Observe: Type “H2” into the Reactants box and hit Enter on your keyboard. Note that the formula is shown as H 2 below. The small “2” in H 2 is a subscript.
A. What does the “2” in H 2 represent? _______________________________________
B. In general, what do you think a subscript in a chemical formula tells you? _________
C. Try typing in other subscripts next to the H, such as 3, 4, and 5. Is your answer to
question B still true? Explain. ____________________________________________
- Count: Clear the Reactants box, and type in a more complex chemical formula: “Ca(OH)2.” Look at the number of atoms shown.
A. How many of each type of atom do you see? Ca: _____ O: _____ H: _____
B. In general, what happens when a subscript is found outside of parentheses?
C. Try typing in other subscripts next to the (OH), such as 3, 4, and 5. Is your answer to
question B still true? Explain. ____________________________________________
- Practice: For each of the real chemical formulas below, calculate how many of each element there are. Check your answers for the first three formulas using the Gizmo.
AgCl 3 Cu 2 Ag: _____ Cl: _____ Cu: _____
Ba(AsO 4 ) 2 Ba: _____ As: _____ O: _____
(NH 4 ) 3 PO 4 N: _____ H: _____ P: _____ O: _____
MnPb 8 (Si 2 O 7 ) 3 Mn: _____ Pb: _____ Si: _____ O: _____
There are two hydrogens.
How many of an element there is.
Yes. It would make it to where there is 3,4, and 5 Hydrogens.
1 2 2
You times it by number in parentheses.
Yes. I would times 1 by 3,4, and 5.
1 3 2
1 2 8
3 12 1 4
1 8 6 21
Activity B (continued from previous page)
- Practice: Chemical reactions are generally classified into five groups, defined below. Balance each equation, using the Gizmo for help.
Combination (or synthesis ) – two or more elements combine to form a compound.
Na + O 2 Na 2 O _________________________________________
La 2 O 3 + H 2 O La(OH) 3 _________________________________________
N 2 O 5 + H 2 O HNO 3 _________________________________________
Decomposition – a compound breaks down into elements and/or simpler compounds.
KNO 3 KNO 2 + O 2 _________________________________________
NaN 3 Na + N 2 _________________________________________
NH 4 NO 3 N 2 O + H 2 O _________________________________________
Combustion – a fuel reacts with oxygen to release carbon dioxide, water, and heat.
CH 4 + O 2 CO 2 + H 2 O _________________________________________
C 3 H 8 + O 2 CO 2 + H 2 O _________________________________________
C 6 H 12 O 6 + O 2 CO 2 + H 2 O _________________________________________
Single replacement – an element replaces another element in a compound.
KCl + F 2 KF + Cl 2 _________________________________________
Mg + HCl MgCl 2 + H 2 _________________________________________
Cu + AgNO 3 Cu(NO 3 ) 2 + Ag _________________________________________
Double replacement – two compounds switch parts with one another.
AgNO 3 + K 2 SO 4 Ag 2 SO 4 + KNO 3 ___________________________________
Mg(OH) 2 + HCl MgCl 2 + H 2 O ___________________________________
Al(OH) 3 + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2 O ___________________________________
4Na + O2-> 2Na2O
La2O3 + 3H2O ->2 La(OH)
N2O5 + H2O -> 2HNO
2KNO3-> 2KNO2 + O
2NaN3 -> 2Na + 3N
NH4NO3-> N2O + 2H2O
CH4 + 2O2 -> CO2 +2 H2O
C3H8 + 5O2 -> 3CO2 + 4H2O
C6H12O6 + 6O2-> 6CO2 + 6H2O _
2KCl + F2 -> 2KF + Cl
Mg + 2HCl -> MgCl2 + H
Cu + 2AgNO3 -> Cu(NO3)2 +2 Ag
2AgNO3 + K2SO4->Ag2SO4 + 2KNO
Mg(OH)2 + 2HCl-> MgCl2 + H2O
2Al(OH)3 + H2SO4-> Al2(SO4)3 + H2O
Activity C:
Molar mass
Get the Gizmo ready: Erase the chemical formulas in each text box. In the middle menu, select Molar mass.
Introduction: Chemists are often interested in obtaining a certain mass of product from a chemical reaction without wasting any reactants. But how is this done? To calculate the masses of reactants needed for a desired mass of product, it is necessary to understand a unit of quantity called the mole.
Question: How do chemists know how much of each substance to mix?
- Observe: The mass of a molecule of a substance is its molecular mass (M). Molecular mass is measured in universal mass units (u). One universal mass unit (1 u) is approximately the mass of a proton. Hydrogen gas has a molecular mass of 2 u.
A. Type the formula “H2” into the Reactants box. What is the molar mass of hydrogen
gas, H 2? ________________________
B. What is the relationship between the molecular mass and the molar mass of a
substance? _________________________________________________________
A mole is defined as 6 × 10 23 molecules (or atoms) of a substance. This value, called Avogadro’s number , is special because a mole of a substance has a mass in grams that is equal to the molecular mass of the substance. Moles are handy because a mole of one substance contains the same number of particles as a mole of another substance.
- Gather data: The balanced equation to synthesize water is: 2H 2 + O 2 2H 2 O. Use the Gizmo to find the molar masses of each substance in this equation:
2H 2 __________ O 2 __________ 2H 2 O __________
- Analyze: Based on the molar masses, how can you tell that an equation is balanced?
- Apply: Suppose you had one mole of oxygen (O 2 ). How many moles of hydrogen (H 2 ) would react completely with the oxygen, and how many moles of H 2 O would be produced?
(Activity C continued on next page)
2
Molar mass is mass of atoms. Molecular mass is how many elements there are.
4 32 36
If they have the same mass all together.
1 mole. 1 mole of H2O
Chem Equations Gizmo Virtual Assignment
Course: General Chemistry I (CHEM 1110)
University: Pellissippi State Community College
