[[CHEM]] Metal questions

2009-01-18 4:54 am

Q1)
1.5 mole of a metallic element Y react with 12 g of oxygen to form an oxide. What is the simplest formula of the oxide?

A: YO
B: YO2
C: Y2O
D: Y2O3

Q2)
2.60 g of a metal X combine with 1.20g of oxygen to form an oxide in which the oxidation number of X is +3, What is the relative atomic
mass of X?

A: 11.6
B: 34.7
C: 52.0
D:104
(relative atomic mass of O =16.9)

我想要STEPS同解釋唔該哂=]

更新1:

點解2條數入面計既係no.of mole of O而唔係no.of mole of O2 既?

回答 (1)

老爺子

2009-01-18 5:22 am

✔ 最佳答案

Q1)
The answer is C.

Mole ratio Y : O
= 1.5 : 12/16
= 1.5 : 0.75
= 2 : 1

Simplest formula = Y2O

Q.2
The answer is B.

The oxide contains X3+ and O2‑.
Therefore, the simplest formula of the oxide is X2O3.

Let the relative of atomic mass of X be y.

Mole ratio X : O
2.6/y : 1.2/16 = 2 : 3
2(1.2/16) = 2(2.6/y)
2(1.2)y = 2(2.6)(16)
y = 34.7

The relative atomic mass of Y is 34.7
=

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