If you’re struggling with percent

composition, I’ll show you that it really only takes three simple steps. Hello

everyone, I’m Melissa Maribel your personal tutor and in this example we

are calculating percent composition of each element in the compound of

potassium oxide or K2O. Here’s the general formula for percent composition

by mass on top we have the mass of the element divided by the mass of the

compound all multiplied by 100. We will apply this formula to find the percent

composition of potassium and this is what we’ll use. Step 1: Find the total

mass of the element. Using our periodic table we’ll find the molar mass of

potassium and since there’s a two subscript in K2O

we must multiply 2 times the molar mass of potassium and we get 78.20. Step two: Find the total mass of the compound. To find the total

mass of the compound we need to find each individual mass of each element and

add them together. So we already found potassium we now need oxygens mass so

looking at our periodic table oxygens mass is 16.00, so we will

add the total mass of each element together to get our total mass of the

compound which is this. Step 3: Plug everything into the formula so we’ll

plug in the total mass of potassium and the total mass of the compound and then

make sure to divide first then multiply the answer by 100 and we’ll round to

four sig figs to get this for our percent composition of potassium but we

still need oxygens percent composition. So let’s set that up for oxygen we

previously found the total mass of the compound we also know the total mass of

oxygen is 16.00, now let’s divide both of those values and then

multiply by 100 and we will get our percent composition of oxygen rounded to

four sig figs. So here are the percent compositions of each element. If you’re

up for a little bit of a challenge then this other video

is for you and remember stay determined you can do this!

Thank you! My chem teacher was making this percent composition diff but when i watched your vid this %comp become easyyyyyyyyy

perfect

good job melissa, cus u make quick and easy

Verrrrrrry colorful

I like it 👏🏼👏🏼👏🏼

If when both of the percentages are added up and they don’t equal 100, does it mean it’s wrong? And plus do we have to round? Thx love ur vids‼️‼️‼️

Thank you for your amazing videos! You are a great help! 😇 God bless you!

i love the transitions but the whole lesson came fast to the point that i slow it down to 0.75

Girl if your channel didn't exist I would be failing chemsitry, I hate high school

Very nice video but can you use these in a real equation lol? Like a reactant and product equation. I can’t find a video that teaches it well

Miss you are best

Good teacher

omg i love her energy!!! It makes me want to actually continue doing level 2 Chemistry

Ughh, you make me so motivated to keep on pushing forward in Chemistry this semester!! God Bless you so much Melissa, I appreciate you! <3 <3

Anyone here writing their chemistry final exam soon too

I am from india and I love your method of teaching