Question

h₂o 18.02g/mol ch₄ 16.05g/mol h₂co₃ 62.03g/mol c₆h₁₂o₆ 180.18g/mol
activity b:
canceling units
get the gizmo ready:

• check that the equation is still:

fe₂o₃ + 3co → 2fe + 3co₂
introduction: while solving problems in stoichiometry, it is useful to pay attention to the units of the ansy
the process of comparing units is called dimensional analysis. a common technique involves using
conversion factors to convert from one unit to another. units that appear in the numerator and denomin
a fraction can be canceled out. for example, converting 2 moles of carbon monoxide to grams involves
multiplying by a conversion factor:
2 mol co • 28.01 g co / 1 mol co = 56.02 g co
all conversion factors are equivalent to one. for example, the conversion factor given above is equivaler
one because the numerator (28.01 g co) and denominator (1 mol co) represent the same amount of c
“mol co” unit is canceled, leaving an answer unit of grams.
question: how do we solve problems in stoichiometry?

1. observe: the first question is: “how many moles of carbon monoxide (co) are required to react com

with 1.75 moles of iron (iii) oxide (fe₂o₃)?” (if this is not the question you see, click new question ur
appears.)
a. what unit is given in the question? mol
b. what quantity is asked for? mol of co

1. find: look for the conversion factor that contains the units “mol fe₂o₃” on top and “mol co” on the bi

drag the tile containing this factor down to the green strip at the bottom.
according to the tile, how many moles of co react with one mole of fe2o3? 3 mol

1. analyze: to get an answer in moles of co, you need to cancel the moles of fe₂o₃. turn on show un

a. what units are given to the right of the equals sign?
b. if these aren’t the units you want, click flip tile. what unit is given now?

1. calculate: if the units are correct, multiply or divide the numbers to solve the problem.

a. how many moles of co will react with 1.75 moles of fe₂o₃? 5.25 mol

Explanation:

Step1: Analyze the chemical equation

The balanced chemical equation is \(Fe_{2}O_{3}+3CO
ightarrow 2Fe + 3CO_{2}\). From this equation, the mole ratio of \(Fe_{2}O_{3}\) to \(CO\) is \(1:3\).

Step2: Set up the conversion

We have \(1.75\) moles of \(Fe_{2}O_{3}\). Using the mole ratio \(\frac{3\space mol\space CO}{1\space mol\space Fe_{2}O_{3}}\) (derived from the balanced equation), we calculate the moles of \(CO\) as \(1.75\space mol\space Fe_{2}O_{3}\times\frac{3\space mol\space CO}{1\space mol\space Fe_{2}O_{3}}\).

Step3: Perform the calculation

$$1.75\times3 = 5.25$$

Answer:

\(5.25\space mol\)