Respuesta :

We are asked to calculate the number of moles in a given mass of a substance. To be able to calculate it, we need the molar mass of the substance. For (NH4)2Cr2O7, the molar mass would be 252.07 g/mol. We calculate as follows:

0.025 g 
(NH4)2Cr2O7 ( 1 mol / 252.07 g ) = 0.0001 mol (NH4)2Cr2O7

Hope this answers the question. Have a nice day.

Moles can be defined as the mass of a compound with respect to molar mass. The moles of [tex]\rm (NH_4)_2Cr_2O_7[/tex] are [tex]\rm \bold{9.91\;\times\;10^{-5}}[/tex].

What is the molecular mass of the compound?

The molecular mass of the compounds is the mass of each element in the formula unit.

The molecular mass of [tex]\rm (NH_4)_2Cr_2O_7[/tex] is 252.06 g/mol.

The moles of the compound can be given as:

[tex]\rm Moles=\dfrac{Mass}{Molar\;mass}[/tex]

The mass of [tex]\rm (NH_4)_2Cr_2O_7[/tex] given is 0.025 g. The moles of [tex]\rm (NH_4)_2Cr_2O_7[/tex] are:

[tex]\rm Moles=\dfrac{0.025\;g}{252.06\;g/mol} \\Moles=9.91\;\times\;10^{-5}\;mol[/tex]

The moles of [tex]\rm (NH_4)_2Cr_2O_7[/tex] in 0.025-gram sample are [tex]\rm \bold{9.91\;\times\;10^{-5}}[/tex].

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