Balancing Chemical Equations
What are the coefficients needed to balance the chemical equation:
__Na + __O2 → __Na2O
4, 1, 2
How do you know the value for mole ratio?
Coefficients in the balanced chemical equation
In your dimensional analysis, where does the given always go?
Top left box
Set up and show out the 1-step dimensional analysis. 2Ag + H2S ---> Ag2S + H2
How many atoms of silver (Ag) are used in a reaction that uses 1.5 mol Ag?
9.03 x 1023 atoms Ag
OR
9.03 E 23 atoms Ag
How do you solve LR and ER problems?
What are the coefficients needed to balance the chemical equation:
__LiCl + ___AlN → __Li3N + __ AlCl3
3, 1, 1, 1
How do you know the value of avogadro’s number?
It’s always 6.02 x 1023
In your dimensional analysis, where does the equivalence statement always go?
In the right boxes
Set up and show out the 1-step dimensional analysis. Cu + 2AgNO3 ---> Cu(NO3)2 + 2Ag
How many moles of Ag will be produced if 14.33 moles of Cu is reacted?
28.66 moles Ag
What is the limiting reactant(s) in the recipe:
2 bread + 6 meat + 1 lettuce --> 1 sandwich
If you have 30 slices of bread, 45 slices of meat, and 20 pieces of lettuce?
MEAT - makes only 7.5 sandwiches
30 bread = 15 sandwiches
20 lettuce = 20 sandwiches
bread and lettuce are in excess. We are limited by the amount of meat we have.
What are the coefficients needed to balance the chemical equation:
__Ba + ___GaPO4 → ___Ba3(PO4)2 + __Ga
3, 2, 1, 2
How do you know the value for molar mass?
You calculate it using the amount (subscript) and the mass on the periodic table.
In dimensional analysis, which units always cancel out?
The given units, the units we are converting “from”
Set up and show out the 2-step dimensional analysis. 2C2H6 + 7O2 ---> 4CO2 + 6H2O
If 8.0 moles of carbon dioxide (CO2) are produced, how many grams of water (H2O) are also produced?
216.24 grams H2O
In the balanced chemical equation
CH4 + 2 O2 --> CO2 + 2 H2O
If you have 3.4 moles of CH4 and 7.1 moles of O2, what is your limiting reactant?
3.4 moles of CH4 = 3.4 moles CO2 (or 6.8 moles H2O)
7.1 moles O2 = 3.55 moles CO2 (or 7.1 moles H2O)
LR = CH4
ER = O2
What are the coefficients needed to balance the chemical equation:
__K2S + __AlBr3 → __ Al2S3 + __KBr
3, 2, 1, 6
If you wanted to convert from moles of strawberries to moles of blueberries, what equivalence statement(s) would you use?
Mole Ratio ONLY
Set up but do not solve for the number of gormbuls, if we are given 433 trembarrs and you can exchange 14 trembarrs for 3 gormbuls.
433 trembars x (3 gormbuls/14 trembarrs)
Set up and show out the 3-step dimensional analysis. Pb(NO3)2 + 2KI ---> PbI2 + 2KNO3
How many grams of PbI2 will be formed if 1.2044 x 1024 molecules of potassium iodide (KI) react?
460.16 g PbI2
In the balanced chemical equation
Mg + O2 --> 2 MgO
If we start with 14.5 grams of Mg and 18.4 grams O2, what is the LR? What is the ER?
14.5 grams Mg = 0.59 moles Mg = 1.19 moles MgO
18.4 grams O2 = 0.57 moles O2 = 1.15 moles MgO
O2 = LR
Mg = ER
What are the coefficients needed to balance the chemical equation:
__MoS2 + __O2 → __MoO + __SO2
2, 5, 2, 4
If you wanted to convert from pieces of avocados to mass of guacamole, what equivalence statement(s) would you use?
Avogadros, Mole Ratio, Molar Mass
Set up and solve the multistep dimensional analysis problem - if the average heart beats 70 times in 1 minute, how many times does it beat in 1 year?
1 year x (365 d/1 year) x (24 h / 1 d) x (60 min/ 1 hr) x (70 beats/1 min) = 36,792,000 beats
Set up and show out the 3-step dimensional analysis. 3CaCl2 + 2Na3PO4 ---> Ca3(PO4)2 + 6NaCl
Problem: If 145.3 grams of sodium chloride (NaCl) are produced, how many grams of Ca3(PO4)2 should also be formed?
128.53 g Ca3(PO4)2
In the balanced chemical equation
3 Li + K3PO4 --> 3 K + Li3PO4
how many grams of K will form is 14.5 grams of Li reacts with 1.98 moles K3PO4?
14.5 grams Li = 2.1 moles Li = 2.1 moles K
1.98 moles K3PO4 = 0.66 moles K
K3PO4 is the LR.
0.66 moles K = 25.8 grams K