Question

In a coin factory, a machine takes 2kg block of zinc. It then

divides this into rectangles each weighing 8g. These rectangles
are then stamped into discs of zinc each weighing 5g with the
remaining zinc discarded.
These zinc discs are then stamped with collectable designs and
next packed into bags of 6 which are sealed and finally packed
into boxes, each containing 4 bags ready for delivery to various
coin collecting shops.
What percentage weight of zinc out of the original block will
be contained in all of the COMPLETELY FILLED boxes
combined?
A) 40%
B) 45%
C) 50%
D) 55%

Answer 1

The question is related to a chemical reaction used in the recovery of silver, and we need to calculate the moles and mass of Zn(CN)2 produced from 35.27 g of K[Ag(CN)₂]. The calculations involve using molar masses, stoichiometry of the reaction, and Avogadro's number to determine the number of molecules and mass of Zn(CN)₂ formed.

Step-by-step explanation:

The question pertains to a chemical reaction where silver is being recovered from K[Ag(CN)₂] using zinc. We're asked to determine how many molecules and what mass of Zn(CN)₂ are produced when 35.27 g of K[Ag(CN)₂] reacts.

Firstly, we calculate the molar mass of K[Ag(CN)₂]. Using the periodic table, we find the combined mass of all atoms in one mole of the compound. This allows us to determine how many moles are in 35.27 g. Applying the stoichiometry of the given reaction, we'll know how many moles of Zn(CN)₂ are produced, and from Avogadro's number, we'll calculate the number of molecules.

Upon having the moles of Zn(CN)₂, we calculate its mass by multiplying the moles with its molar mass. This gives us the mass in grams of Zn(CN)₂ that forms from the reaction.The significance of understanding this reaction is exemplified in the minting of coins, among other applications.