Answer:
<em>1) Molecular weight: 18g/mol </em>
<em>Density: at room temperature (25ºC) is 0.997g/mL</em>
<em>Moles: 0.55moles</em>
<em>2) Molecular weight: 182g/mol</em>
<em>Density: at room temperature (25ºC) is 1.11g/mL</em>
<em>Moles:
</em>
Explanation:
1) The molecular formula of water is
thus, the molecular weight is the sum of the weights of its atoms.
H: 1g/mol x 2 = 2g/mol
O: 16g/mol x 1 = 16g/mol
: 2g/mol + 16g/mol = 18g/mol
The density (δ) of water at room temperature (25ºC) is 0.997g/mL
Therefore, the weight (m) of 1mL of water is:
m = δ.V = ![0.997\frac{g}{mL}. 1mL = 0.997g](https://tex.z-dn.net/?f=0.997%5Cfrac%7Bg%7D%7BmL%7D.%201mL%20%3D%200.997g)
Multiplying the mass by its molecular weight gives the number of moles:
![\frac{0.997g }{18g/mol} = 0.55 moles](https://tex.z-dn.net/?f=%5Cfrac%7B0.997g%20%7D%7B18g%2Fmol%7D%20%3D%200.55%20moles)
2) The molecular formula of benzophenone is
thus, the molecular weight is the sum of the weights of its atoms.
C: 12g/mol x 13 = 156g/mol
H: 1g/mol x 10 = 10g/mol
O: 16g/mol x 1 = 16g/mol
: 156g/mol + 10g/mol + 16g/mol = 182g/mol
The density (δ) of water at room temperature (25ºC) is 1.11g/mL
Multiplying the mass by its molecular weight gives the number of moles:
![\frac{0.04g }{182g/mol} = 2.2x10^{-4}moles](https://tex.z-dn.net/?f=%5Cfrac%7B0.04g%20%7D%7B182g%2Fmol%7D%20%3D%202.2x10%5E%7B-4%7Dmoles)