The amount of matter in an object is consisted to be MASS .
ΔΗ= -115.6 kJ/mol
H2 has a Mr of 2, so as mol=mass/mr we can work out that there are 4 moles of H reacting
Therefore we multiply -115.6 by 4 = -462.4
Answer: 2.26x 10²⁴ atoms C
Explanation: To get the number of atoms,
First we convert mass of C to moles
45g C x 1mole C / 12 g C
= 3.75 moles C
Cancel g of C
Next convert moles of C to atoms using Avogadro's Number.
3.75 moles C x 6.022x10²³ atoms C / 1 mole C
Cancel out the units of moles C.
= 2.26x 10²⁴ atoms of C
In this case, you are given the density( 11.3g/cm3) and the weight (1kg) of the lead. You are asked to find the volume of the lead.
To find volume you need to divide the weight with the density. It would be:
volume= weight/density
volume = 1kg x (1000 gram/kg) / (11.3g/cm3)= 88.495 cm3
