Chemistry Stoichiometry (Pre U Plus)

Which statement is correct?

A Cl has relative isotopic mass of 35.5

B MgCl2 has relative molecular mass of 95.3

C Cl2 has relative molecular mass of 70

D SO3 has relative molecular mass of 80.1

• A

• B

• C

• D

How many oxygen atom does 0.75 mol of sulfur dioxide have?

• 4.15 x 10^23

• 4.52 x 10^23

• 9.03 x 10^23

• 1.35 x 10^24

A sports medal has a total surface area of 100 cm². It was evenly coated with silver electrolysis. Its mass increased by 0.316 g.

How many atoms of silver were deposited per cm² on the surface of the medal? medal?

• 1.54 x 10^23

• 1.76 x 10^19

• 3.00 x 10^21

• 3.00 x 10^23

A washing powder contains sodium hydrogencarbonate, NaHCO3​, as one of the ingredients.

In a titration, a solution containing 1.00 g of this washing powder requires 10 cm³ of 0.200 moldm⁻³ sulfuric acid for complete reaction. The sodium hydrogencarbonate is the only ingredient that reacts with the acid.

What is the percentage by mass of sodium hydrogencarbonate in the washing powder?

• 33.6%

• 12.0%

• 16.8%

• 6.8%

• 11.32

• 8.18

• 0.06

• 0.12

The airbags in Cars contain sodium azide, NaN₃, and an excess of potassium nitrate, KNO₃.In a car accident, the reactions shown occur, producing nitrogen. This causes the airbag to inflate rapidly.

 

2NaN₃ → 2Na + 3N₂
10Na + 2KNO₃ → K₂O + 5Na₂O + N₂

How many moles of nitrogen gas are produced in total when 1 mol of sodium azide, NaN₃, decomposes in an airbag?

• 3.2

• 4.0

• 1.5

• 1.6