Photographic film contains silver bromide in gelatin. Once exposed, some of the silver bromide decomposes, producing fine grains of silver. The unexposed silver bromide is removed by treating the film with sodium thiosulfate. Soluble sodium silver thiosulfate (Na3Ag(S2O3)2) is produced.
AgBr(s) + 2 Na2S2O3(aq) Na3Ag(S2O3)2(aq) + NaBr(aq)
Determine the mass of Na3Ag(S2O3)2 produced if 0.430 g AgBr is removed.
Here is a solved example of a stoichiometry problem such as this one. Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html
Chloroform (CHCl3), an important solvent, is produced by a reaction between methane and chlorine.
CH4(g) + 3 Cl2(g) CHCl3(g) + 3 HCl(g)
How many grams of CH4 is needed to produce 39.0 g CHCl3?
To determine the mass of Na3Ag(S2O3)2 produced when 0.430 g AgBr is removed, we need to calculate the stoichiometric ratio between AgBr and Na3Ag(S2O3)2.
The balanced chemical equation for the reaction is:
AgBr(s) + 2 Na2S2O3(aq) → Na3Ag(S2O3)2(aq) + NaBr(aq)
From the balanced equation, we can see that the stoichiometric ratio between AgBr and Na3Ag(S2O3)2 is 1:1. This means that for every 1 mole of AgBr, we will get 1 mole of Na3Ag(S2O3)2.
To calculate the moles of AgBr, divide the given mass of AgBr by its molar mass. The molar mass of AgBr can be calculated as follows:
Ag = 107.87 g/mol
Br = 79.90 g/mol
Molar mass of AgBr = 107.87 g/mol + 79.90 g/mol = 187.77 g/mol
Now, calculate the moles of AgBr:
Moles of AgBr = Mass of AgBr / Molar mass of AgBr
Moles of AgBr = 0.430 g / 187.77 g/mol
Next, since the stoichiometric ratio between AgBr and Na3Ag(S2O3)2 is 1:1, the moles of Na3Ag(S2O3)2 produced will be equal to the moles of AgBr.
Finally, calculate the mass of Na3Ag(S2O3)2 using its molar mass. The molar mass of Na3Ag(S2O3)2 can be calculated as follows:
Na = 22.99 g/mol
Ag = 107.87 g/mol
S = 32.07 g/mol
O = 16.00 g/mol
Molar mass of Na3Ag(S2O3)2 = (3 * 22.99 g/mol) + 107.87 g/mol + (2 * 32.07 g/mol) + (6 * 16.00 g/mol)
Multiply the moles of AgBr by the molar mass of Na3Ag(S2O3)2 to get the mass of Na3Ag(S2O3)2 produced.
Now, let's calculate the mass of Na3Ag(S2O3)2:
Mass of Na3Ag(S2O3)2 = Moles of AgBr * Molar mass of Na3Ag(S2O3)2
Remember to use the correct number of significant figures throughout the calculations.