How can I find the actual percent composition of magnesium oxide?

Answer 1

Here's how you can do that.

A compound's percent composition essentially tells you how many grams of each constituent element you get per #"100 g"# of compound.
#color(blue)(|bar(ul(color(white)(a/a)"% element i" = "mass of i"/"mass of compound" xx 100color(white)(a/a)|)))#

This means that in order to find a compound's percent composition, you need to pick a sample and use

Now, magnesium oxide, #"MgO"#, has a molar mass of #"40.3044 g mol"^(-1)#, which means that one mole of magnesium oxide has a mass of #"40.3044 g"#.

This will be your sample of magnesium oxide. Notice that one mole of magnesium oxide contains

The molar masses of the two elements are

#M_("M Mg") = "24.3050 g mol"^(-1)#
#M_("M O") = "15.9994 g mol"^(-1)#
This tells you that one mole of magnesium oxide, i.e. #"40.3044 g"#, will contain
#"24.3050 g Mg" " "# and #" " "15.9994 g O"#

Now you have all that you need to figure out the percent composition of the compound. You will have

#"% Mg" = (24.3050 color(red)(cancel(color(black)("g"))))/(40.3044color(red)(cancel(color(black)("g")))) xx 100 = color(green)(|bar(ul(color(white)(a/a)color(black)("60.304 %")color(white)(a/a)|)))#
#"% O" = (15.9994color(red)(cancel(color(black)("g"))))/(40.3044color(red)(cancel(color(black)("g")))) * 100 = color(green)(|bar(ul(color(white)(a/a)color(black)("39.696 %")color(white)(a/a)|)))#
You can thus say that #"100 g"# of magnesium oxide will contain
#"60.304 g Mg" " "# and #" " "39.696 g O"#
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Answer 2

The mass of each element can be found by performing a chemical analysis or by using experimental methods like gravimetric analysis or spectroscopy. Once you have the masses of magnesium (Mg) and oxygen (O) in a given sample of magnesium oxide, you can plug them into the formula to calculate their respective percent compositions. The formula for percent composition of Mg is: percent composition of Mg = (mass of Mg / total mass of magnesium oxide) x 100%; for percent composition of O, it is: mass of O / total mass of magnesium oxide) x 100%.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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