I still don't understand how to do this problem; grams/molar mass I understand, but I need to see the steps CLEARLY.

43. How many moles are in 25.0 grams of potassium? Show your work and round your answer to the appropriate number of significant figures.

Please, please help with this!
Thanks
-MC

a mole of any chemical is its atomic or molecular mass in grams.

a mole of K is 39.0983 grma

Moles of K in 25 g= 25/39.0983

hey mysterychicken i think we go to the same school :) i have the exact same history questions on my tests.

send me an email, we could prolly help eachother out. seanned2009 at gmail

To find the number of moles in a given mass of a substance, you need to use the formula:

moles = mass (in grams) / molar mass (in grams per mole)

In this case, you are asked to find the number of moles of potassium, given a mass of 25.0 grams.

Step 1: Find the molar mass of potassium
The molar mass of an element is the mass of one mole of that element. The molar mass of potassium (K) is approximately 39.10 grams per mole.

Step 2: Plug the values into the formula
moles = 25.0 grams / 39.10 grams per mole

Step 3: Calculate the answer
Divide 25.0 grams by 39.10 grams per mole to find the number of moles.

moles = 0.6397 moles

Step 4: Round the answer
The question asks you to round your answer to the appropriate number of significant figures. Since the given mass is given to three significant figures, you should round your answer to three significant figures as well.

moles = 0.640 moles

So, there are approximately 0.640 moles of potassium in 25.0 grams of potassium.