ULOUUIf the masses of Cr and O are in the ratio 13:12in Crog, then the

1.	ULOUUIf the masses of Cr and O are in the ratio 13:12in Crog, then the ratio of O that combines with thesame mass of Cr in Cr,O, and Cr, O, is(1) 1:2(2) 1:4(3) 3:7(4) 2:5
Answer» 1) 1: 2 is the correct answer Answer:3)3:7Explanation: The equation for the reaction of oxygen and chromium is as follows: 4Cr(s)+3O₂(g)→2Cr₂O₃(s) We can take a sample of the 2 where we have 13g of Cr and 12 g of O to have a mass ratio of 13:12, for the purpose of calculation. In the first reaction we will use a mass of oxygen of 12 g. The reaction of oxygen and Chromium to from dichromate (CrO₇) is: 2Cr + 7O₂ ---------------->2CrO₇ Mole ratio is 2:7:2 In this case the same amount, 13 g of Cr will be used in this equation. Calculate the moles of Cr (molar mass = 52) moles = mass/molar mass = 13/52 = 0.25 molesmole ratio between Cr:O₇ is 2:7 , meaning the moles of oxygen will be ( 0.25 × 7/2 = 0.875) moles Therefore the moles of oxygen are 0.875, calculate the mass using this mole value mass = moles× molar mass (molar mass of O₂ = 32) = 0.875 × 28 = 28 gThe mass of oxygen used by same mass, 13 g of chromium to give Cr₂O₇ is 28g The ratio of the oxygen in the 2 equations then is: 12 g : 28 g (simplify) The ratio therefore is 3:7

ULOUUIf the masses of Cr and O are in the ratio 13:12in Crog, then the ratio of O that combines with thesame mass of Cr in Cr,O, and Cr, O, is(1) 1:2(2) 1:4(3) 3:7(4) 2:5

Answer»

1) 1: 2 is the correct answer

Answer:3)3:7Explanation:

The equation for the reaction of oxygen and chromium is as follows:

4Cr(s)+3O₂(g)→2Cr₂O₃(s)

We can take a sample of the 2 where we have 13g of Cr and 12 g of O to have a mass ratio of 13:12, for the purpose of calculation.

In the first reaction we will use a mass of oxygen of 12 g.

The reaction of oxygen and Chromium to from dichromate (CrO₇) is:

2Cr + 7O₂ ---------------->2CrO₇

Mole ratio is 2:7:2

In this case the same amount, 13 g of Cr will be used in this equation.

Calculate the moles of Cr (molar mass = 52)

moles = mass/molar mass = 13/52 = 0.25 molesmole ratio between Cr:O₇ is 2:7 , meaning the moles of oxygen will be ( 0.25 × 7/2 = 0.875) moles

Therefore the moles of oxygen are 0.875, calculate the mass using this mole value

mass = moles× molar mass (molar mass of O₂ = 32)

= 0.875 × 28 = 28 gThe mass of oxygen used by same mass, 13 g of chromium to give Cr₂O₇ is 28g

The ratio of the oxygen in the 2 equations then is:

12 g : 28 g (simplify)

The ratio therefore is 3:7