Silver tarnishes (turns to Ag2S) in the presence of oxygen and hydrogen sulfide according to the following equation:
4Ag(s) + 2H2S(g) + O2(g) �¨ 2Ag2S(s) + 2H2O(l)
Usually, H2S is the limiting reactant. If a silver spoon is placed in a container that holds 56.7mL of H2S at 1.23atm and 22�‹C, how many grams of silver on the spoon will tarnish
Use PV = nRT and solve for n = number of mols H2S at the conditions listed. Then convert mols H2S to mols Ag using the coefficients in the balanced equation. Finally, g Ag = mols Ag x atomic mass Ag.
16.172 grams
To find out how many grams of silver will tarnish, we need to determine the amount of H2S available and use the stoichiometry of the reaction.
Step 1: Convert the volume of H2S gas to moles.
We can use the ideal gas law to convert the volume of H2S gas to moles.
PV = nRT
Where:
P = pressure (1.23 atm)
V = volume (56.7 mL or 0.0567 L)
n = moles of gas
R = gas constant (0.0821 L·atm/(mol·K))
T = temperature in Kelvin (22°C + 273 = 295 K)
Substituting the values, the equation becomes:
1.23 atm * 0.0567 L = n * 0.0821 L·atm/(mol·K) * 295 K
Solving for n, we get:
n = (1.23 atm * 0.0567 L) / (0.0821 L·atm/(mol·K) * 295 K)
Step 2: Calculate the moles of Ag using the stoichiometry of the reaction.
From the balanced equation, we know that the stoichiometric ratio between H2S and Ag is 2:4. Therefore, the moles of Ag will be half the moles of H2S.
moles of Ag = 0.5 * moles of H2S
Substitute the value of moles of H2S we calculated into this equation.
Step 3: Calculate the mass of Ag in grams.
We know that the molar mass of Ag is 107.87 g/mol. To find the mass of Ag in grams, we multiply the moles of Ag by the molar mass.
mass of Ag = moles of Ag * molar mass of Ag
Substitute the value of moles of Ag we calculated into this equation.
By following these steps, you should be able to calculate the grams of silver that will tarnish.
To determine the number of grams of silver that will tarnish, we need to use the given information and perform a stoichiometric calculation.
1. Convert the given volume of H2S to moles:
The ideal gas law, PV = nRT, can be used to convert the volume of H2S to moles.
PV = nRT
n = PV / RT
Given:
Volume of H2S, V = 56.7 mL = 0.0567 L
Pressure, P = 1.23 atm
Temperature, T = 22°C = 295 K (convert to Kelvin by adding 273)
n = (1.23 atm * 0.0567 L) / (0.0821 L·atm/mol·K * 295 K)
2. Determine the moles of Ag using the stoichiometry of the balanced equation:
From the balanced equation, 4 moles of Ag react with 2 moles of H2S to produce 2 moles of Ag2S.
Since H2S is the limiting reactant, we can determine the moles of Ag by using the ratio of moles of H2S to moles of Ag (2:4).
moles of Ag = (n of H2S) * (4 moles of Ag / 2 moles of H2S)
3. Calculate the mass of Ag in grams:
To convert moles of Ag to grams, we need to multiply by the molar mass of Ag (atomic weight of Ag = 107.87 g/mol).
mass of Ag = (moles of Ag) * (molar mass of Ag)
Now, let's calculate the values step by step:
Step 1: Convert the given volume of H2S to moles:
V = 0.0567 L
P = 1.23 atm
T = 295 K
n = (1.23 atm * 0.0567 L) / (0.0821 L·atm/mol·K * 295 K)
n ≈ 0.002286 moles of H2S
Step 2: Determine the moles of Ag:
moles of Ag = (0.002286 moles of H2S) * (4 moles of Ag / 2 moles of H2S)
moles of Ag ≈ 0.004572 moles
Step 3: Calculate the mass of Ag in grams:
molar mass of Ag = 107.87 g/mol
mass of Ag = (0.004572 moles of Ag) * (107.87 g/mol)
mass of Ag ≈ 0.4923 grams
Therefore, approximately 0.4923 grams of silver on the spoon will tarnish.