Cliffs AP Chemistry, 3rd Edition

Step 2:Write a balanced chemical equation that describes the reaction.

silver + chlorine gas yields silver chloride.

22 Ag s^h+Cl g 2 _ i" AgCl s^h

Step 3:Begin to answer the questions asked. Remember to give a brief restatement for each
question, to label each specific question so that the grader knows which question you are an-
swering, and to underline the conclusion(s) where necessary.

1. (a) (1) Restatement: Number of moles of chlorine gas that reacted.
   mass of chlorine that reacted
   = (mass of silver strip + compound) −mass of original silver strip
   1.9342 g −1.7838 g = 0.1504 g of chlorine atoms
   moles of chlorine atoms that reacted = mass of chlorine atoms/atomic mass of chlorine

0.1504 g / 35.45 g ⋅mole–1= 0.004242 mole of chlorine atoms

(a) (2) Restatement: Moles of silver that reacted.

atomic mass of silver

_imass of original silver strip mass of dry strip after washing-

1.7838 g −1.3258 g = 0.4580 g

0.4580 g / 107.87 g ⋅mole–1= 0.004246 mole of silver atoms

(b) Restatement: Empirical formula for silver chloride.

empirical formula = moles of silver atoms / moles of chlorine atoms

.

..
mole of chlorine

mole of silver AgCl

0 004242

0 004246 =1 001"

(c) (1) Restatement: Effect on the empirical formula if some of the white compound

had been washed down the sink before the coated strip was dried and reweighed.

The white product was silver chloride. Had she lost some before she weighed it,

the mass of silver chloride would have been less than what it should have been.

This would have made the number of grams of chlorine appear too low, which

in turn would have made the number of moles of chlorine appear too low. Thus,

in the ratio of moles of silver to moles of chlorine, the denominator would have

been lower than expected and the ratio would have been larger.Because the

mass of the compound does not enter into the calculations for the moles of sil-

ver that reacted, the moles of silver would not have been affected.

Gravimetrics