How many MOLECULES are in 2.00 moles of h2o?

Question

cuanchi · Answer

do you know how many MOLECULES are in one mole of H2O?

thatonegirl_ · Answer

3?

cuanchi · Answer

no, that is the number of atoms in a molecule of water.
Do you know the definition of mole?

cuanchi · Answer

this video is very illustrative about mole https://www.youtube.com/watch?v=TEl4jeETVmg

thatonegirl_ · Answer

its like a way to count an amount of something easier right??

cuanchi · Answer

yes is like a dozen, but in place to have 12 you have 6.02 x 10^23 things

thatonegirl_ · Answer

so how would i figure out how many molecules?

cuanchi · Answer

is like if I ask you how many doughnuts are in two dozens of doughnuts?

thatonegirl_ · Answer

so i multiply them??

cuanchi · Answer

yes

thatonegirl_ · Answer

when does 6.02x10^23 come in?

cuanchi · Answer

what is your final answer?

cuanchi · Answer

that is the definition of mole Mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as the amount of any substance that contains as many elementary entities (e.g., atoms, molecules, ions, electrons) as there are atoms in 12 grams of pure carbon-12 (12C), the isotope of carbon with relative atomic mass of exactly 12 by definition. This corresponds to the Avogadro constant, which has a value of 6.02214129(27)×1023 elementary entities of the substance. It is one of the base units in the International System of Units; it has the unit symbol mol and corresponds with the dimension symbol N. http://en.wikipedia.org/wiki/Mole_(unit)

cuanchi · Answer

take a look at the video that I posted before https://www.youtube.com/watch?v=TEl4jeETVmg

thatonegirl_ · Answer

so 2 moles is 12.04 x10^23 molecules??

thatonegirl_ · Answer

yeah i watched that

cuanchi · Answer

yes!! you can express as 1.204 x 10^24

thatonegirl_ · Answer

oh yeah thats what i meant oops lol, so then i would divide that by the molar mass of h20?

cuanchi · Answer

no you dont need that is the final answer for this problem

thatonegirl_ · Answer

conversation factors?

cuanchi · Answer

6.02 x 10^23 molecules of H2O / 1mol of H2O

thatonegirl_ · Answer

okay and what about the set-up?

cuanchi · Answer

$$2 molesH _{2} O \times \frac{ 6.02\times10^{23} molecules-of H _{2}O}{ 1 mol H _{2}O?}$$

cuanchi · Answer

without the question mark

thatonegirl_ · Answer

okay thank you so much! so my final answer is 1.20x10^24 molecules?

cuanchi · Answer

yes!!!

thatonegirl_ · Answer

ok thanks a ton!

preetha · Answer

Good work Cuanchi!