Question

Sam records the mass of his evaporating dish as 6.251 g.

Answer 1

0.309g

Explanation:

Mass of evaporating dish = 6.251g

Mass of evaporating dish and sample of hydrate = 16.864g

   solving for mass of hydrate before heating;

  Mass of hydrate =

mass of evaporating dish and sample of hydrate - mass of evaporating dish;

 Mass of hydrate before heating = 16.864g - 6.251g = 10.613‬g

Upon heating ;

   Mass of hydrate plus dish = 11.3g

Unknown:

number of moles of water removed from the hydrate = ?

We need to find the mass of water removed from the hydrate;

Mass of hydrate after heating =mass of hydrate plus dish after heating - mass of evaporating dish

mass of hydrate after heating =  11.3g - 6.251g = 5.049g

Mass of water lost = Mass of hydrate before heating - mass of hydrate after heating

    =  10.613‬g - 5.049g

    = 5.564g

Number of moles of water = $\frac{mass}{molar mass} = \frac{5.564}{18}$

number of moles of water = 0.309moles

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Number of moles brainly.com/question/13064292

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