Question

158.5g of chloride occupies a volume of 22.4L at STP. the % of chlorine in this chloride is 44.71%. the atomic weight and valency of the element is .......plz answer fast guys with proper step​

Answer 1

Answer:

The valency of the element is +2

and has an atomic weight of 87.64 amu

(and thus it is probably Strontium.

Explanation:

First step

is to find out how many moles are there in the 158.5g of that unknown substance, to do this we take help from the volume and use the followingrelation .:

$number \: of \: moles \: = \frac{volume \: given}{22.4 {dm}^{3} }$

hence the number of moles

$= \frac{22.4}{22.4} = 1$

(as one liter = one dm3 thus the unit also cancel each other)

Now SECOND STEP

is to find the amount of chlorine in that compound which is given as = 44.71% thus

$grams \: of \: chlorine = \frac{44.71 \times 158.5}{100} \\ = 70.86 \: grams$

STEP THREE

is to conver thus mass of chlorine into moles of chlorine, thus we use another equation, which is .:

$number \: of \: moles = \frac{given \: mass}{molar \: mass} \\ = \frac{70.86}{35.5} = 2 \: mol$

HENCE each mole of the unknown compound contain two moles of chloride and THUS each molecule contain two atoms of chloride,

also we know that charge on each chloride ion is always -1 hence the valency of that compound would be +2

STEP FOUR

is to find the atomic weight of that substance, to do this simply subtract the mass of chlorine from the total mass .:

atomic weight of the unknown element = 158.5 - 70.86 = 87.64

STEP FIVE

if you want to know which element is this simply check it in periodic table and you would find that thus weight is exactly of Strontium.