Question

first student used a carbon pencil to write his homework the mass of this was found to be 5 mg with the help of this calculate number of moles of carbon in his homework writing II the number of carbon atoms in 12 mg of his homework writing

Answer 1

Answer:

The answer is 6.022x10^20

Step-by-step explanation:

Mass of carbon is 0.005g

molar mass of carbon= 12g/mole

moles of carbon= 0.005/12                              (mass/molar mass)

=4.167x10^-4 moles

in 12mg the number of moles= 0.012/12

=0.001mole

number of atoms in 12mg

=0.001x6.022x10^23

=6.022x10^20

                                               

Answer 2

Step 1:

For 5 mg of homework writing -

Step 2: No of C-atoms in 5 mg of homework -

N1 = n1 × NA

N1 = W1 / M × NA

N1 = 5×10^-3 / 12 × 6.022×$10^{23}$

N1 = 2.51×$10^{20}$ atoms

Step 3:

(2) For 12 mg of homework writing -

No of C-atoms in 12 mg of homework -

N2 = n2 × NA

N2 = W2 / M × NA

N2 = 12×10^-3 / 12 × 6.022×$10^{23}$

N2 = 6.022×$10^{20}$ atoms

Step 4:

5 mg, No of C-atoms = 2.51×$10^{20}$ atoms

In 12 mg, No of C-atoms = 6.022 x $10^{20}$ atoms