Question

please answer all and show all the work. thanks

Show the correct number of significant figures and units for all measurements and calculations. A. Empirical formula Mass of crucible and lid 14.59289 14.95279 Mass of crucible, lid, and magnesium Appearance of magnesium ribbon: Appearance of product: 15, 11999 Mass of crucible, lid, and product Calculations (Show your work) Mass of magnesium ribbon (show calculations) Mass of magnesium oxide product (show calculations)

Answer 1

A) Given mass of Crucible, lid and magnesium = 14.9527g

Mass of Crucible and lid = 14.5928g

Mass of magnesium is the difference in mass of these two.

Therefore, mass of magnesium = 14.9527 - 14.5928

= 0.3599 g

~0.36 g

Mass of Crucible, lid and product = 15.1199 g

I) Mass of magnesium oxide product = 15.1199 - 14.5928

= 0.5271 g

II) Mass of magnesium = 0.3599 g

III) Mass of oxygen = mass of product - mass of magnesium

= 0.5271 - 0.3599

= 0.1672 g

IV) Number of moles of magnesium = mass of Mg/atomic Mass of Mg

Number of moles of magnesium = 0.36/24

= 0.015 moles.

V) Number of moles of oxygen = Mass of oxygen/ molecular mass of oxygen

Number of moles of oxygen = 0.1672/32

= 0.005225 moles.

VI) Mole ratio on Magnesium to oxygen = moles of magnesium/moles of oxygen

Mole ratio = 0.015/0.005225

= 2.87.

VII) Empirical formula = Mg_{​​​​​2.87} O

~ Mg_{​​​​​3}​​​​O.

B)

I) Mass of hydrate = Mass of dish with hydrate - mass of empty dish

= 118.3432 - 118.1365

= 0.2067 g

II) Mass of anhydrate = Mass of dish with anhydrate - mass of empty dish

= 118.2337 - 118.1365

= 0.0972 g.

III) Mass of water driven off from hydrate = mass of dish with hydrate - mass of dish with anhydrate

= 118.3432 - 118.2337

= 0.1095 g.

IV) Percent water in hydrate = Mass of water X 100 /Total mass of hydrate.

% of water = 0.1095 X 100 / 0.2067

= 52.975 %.

V) Number of moles of water = mass of water/ molecular mass of water

= 0.1095/18

= 0.006

Note: Molecular mass of anhydrate is not given, hence number of moles of anhydrate can not be calculated, and then empirical formula also.