Question

I got a quick simple chemistry question and help would be awesome :)

Calculate the number of atoms in a 2.76 x 10^3 g sample of calcium.

Answer 1

u know mass number of calcium?

Answer 2

Yeah, the mass is 40.08 amu

Answer 3

calcium: 20 protons and 20 neutrons
mass number: 40

Answer 4

do you know avagadro's number?

Answer 5

6.022 x 10^23

Answer 6

40 gram of calcium contains 6.022 x 10^23 atoms

can you tell how to find number of atoms in 1 gram?

Answer 7

Divide by 40?

Answer 8

yea

6.022 x 10^23/40 is the number of atoms in 1 gram of calcium

so the number of atoms in 2.76 x 10^3 grams is?

Answer 9

So the avagadro's number is the amount in grams?

Answer 10

And also, is the amu in grams too?

Answer 11

u know how to proceed?
no amu is a unit on its own.

if mass number(protons +neutrons) of some element is M, then M grams of the substance contains "6.022 x 10^23" atoms in it.

Answer 12

Ohhh, okay.

Answer 13

So how would I enter it in my calculator?

Answer 14

you will have to do the 10^ stuff by hand

Answer 15

Help please? Not good with scientific notation :(

Answer 16

\[\frac{ 6.022 \times 10^{23} \times 2.76 \times 10^3 }{ 40 }\]

Answer 17

\[\frac{ 6.022 \times 2.76 \times (10^3\times 10^{23}) }{ 40 }\]

Answer 18

do everything outside the brackets by calculator

Answer 19

\[\frac{ 16.621 \times 10^{26}}{ 40 }\]

Answer 20

Good