Question

Silver oxide decomposes when heated to give silver and oxygen: If 0.5 moles of lunar caustic is heated up to 450°C, giving out nitrogen dioxide and oxygen leaving silver as metal, what is the mass of residue?

a) 0.5 grams
b) 17.0 grams
c) 12.5 grams
d) 4.0 grams

Answer 1

Silver oxide decomposes when heated to give silver and oxygen. The mass of the residue (silver) can be calculated using the number of moles of silver oxide and the molar mass of silver. None of the given options match the calculated mass of the residue.

Step-by-step explanation:

Silver oxide decomposes when heated to give silver and oxygen.

The chemical equation for this reaction is: 2Ag2O → 4Ag + O2

From the equation, we can see that 2 moles of Ag2O decompose to give 4 moles of Ag and 1 mole of O2. Since we are given that 0.5 moles of lunar caustic (Ag2O) is decomposed, we can calculate the moles of Ag and O2 produced.

1 mole of Ag2O gives 4 moles of Ag, so 0.5 moles of Ag2O will give 2 moles of Ag.

1 mole of Ag2O gives 1 mole of O2, so 0.5 moles of Ag2O will give 0.5 moles of O2.

To calculate the mass of the residue, we need to find the molar mass of Ag.

The molar mass of Ag is 107.87 g/mol.

So, the mass of the residue (Ag) is 2 moles x 107.87 g/mol = 215.74 g.

Therefore, the correct answer is not given as none of the options provided match the calculated mass of the residue.