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Hello.
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In this question, we are given this balanced equation.
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2mg reacts with o2 to produce 2mgo.
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And we're told that we are reacting 48 grams of the magnesium.
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With the oxygen, we have to assume there's enough oxygen for a complete reaction.
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And we want to know how many grams of magnesium oxide are going to be formed.
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We're starting with a mass and we're trying to find a mass.
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That means this is a mass -to -mass stochometry problem.
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And in a mass -to -mass -to -mastroachymetry problem, we have to use the mole ratio to convert from moles of one thing to moles of something else.
00:45
And we get that mole ratio from the coefficients in the balanced equation.
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This equation shows us that two moles of magnesium will produce two moles of magnesium oxide.
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But before we can use that mole ratio, we have to convert to moles.
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Our first step, therefore, is going to be using the molar mass of magnesium to convert from grams to moles.
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Once we're at moles, then we can convert from moles of magnesium to moles of the magnesium oxide by using that 2 -2 -mole ratio.
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And finally, we can convert to the mass of mgo by using its molar mass.
01:27
We would get that by adding together the mass of one magnesium and one oxygen from the periodic table.
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Okay, so this is our plan.
01:35
Let's go ahead and set this up using dimensional analysis and solve for our answer.
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We are starting out with 48 grams of magnesium.
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Notice that only has two significant figures, so our final answer will need to be rounded to just two significant figures.
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All right, in our first step, we need to use the molar mass.
01:55
Looking at the periodic table, we see that the molar mass of magnesium is 24, rather, 0 .31 grams of magnesium...