Mean titre of 0.2M sodium thiosulphate = 32.2 ml
1) Calculate number of moles of S2O32- which react in the titration
2)Calculate how many moles of I2 react with this amount of S2O3
3)How many Cu2+ ions are needed to liberate this amount of I2? Use this answer as the number of moles of Cu2+ ions in your 25cm3 aliquot of “coin solution”. How many moles of Cu2+ ions were in the 250cm3 of “coin solution”?
4) Knowing that Ar(Cu) = 63.5 – calculate the number of grams of copper in this “coin solution”.
1) Well, first let's convert the volume of the sodium thiosulphate solution to liters. Since there are 1000 mL in a liter, we have 32.2 mL * (1 L / 1000 mL) = 0.0322 L.
Now, we can calculate the number of moles of S2O32- using the molarity (0.2 M) and volume (0.0322 L) of the solution. The formula for calculating moles is moles = molarity * volume. So, moles = 0.2 M * 0.0322 L = 0.00644 moles.
2) Now, let's find out how many moles of I2 react with this amount of S2O32-. According to the balanced equation, each mole of S2O32- reacts with two moles of I2. Therefore, the number of moles of I2 is double the number of moles of S2O32-. So, moles of I2 = 2 * 0.00644 moles = 0.01288 moles.
3) Next, let's determine the number of Cu2+ ions needed to liberate this amount of I2. According to the balanced equation, each mole of I2 reacts with two moles of Cu2+. Therefore, the number of moles of Cu2+ ions is also double the number of moles of I2. So, moles of Cu2+ ions = 2 * 0.01288 moles = 0.02576 moles.
Since we have assumed that the number of moles of Cu2+ ions in the 25 cm3 aliquot of "coin solution" is equal to the number of moles of Cu2+ ions needed to liberate the I2, the answer to the first part is 0.02576 moles of Cu2+ ions.
To find the number of moles of Cu2+ ions in the 250 cm3 of "coin solution," we need to scale up the 25 cm3 answer. Since 25 cm3 is 1/10th of 250 cm3, the number of moles of Cu2+ ions in the 250 cm3 solution is 10 times the number of moles in the 25 cm3 solution. So, moles of Cu2+ ions in the 250 cm3 solution = 10 * 0.02576 moles = 0.2576 moles.
4) Finally, let's calculate the number of grams of copper in the "coin solution." Since one mole of Cu2+ ions is equal to one mole of copper, we can directly use the molar mass of copper (Ar(Cu) = 63.5 g/mol) to find the mass. Mass of copper = moles of Cu2+ ions * molar mass of copper = 0.2576 moles * 63.5 g/mol = 16.360 g.
Therefore, the "coin solution" contains approximately 16.360 grams of copper. I hope these calculations didn't "copper" your enthusiasm for chemistry!
1) To calculate the number of moles of S2O32- that react in the titration, we need to use the given information that the mean titre of 0.2M sodium thiosulphate is 32.2 ml.
First, convert the volume from milliliters to liters:
32.2 ml = 32.2/1000 = 0.0322 L
Now, we can calculate the number of moles of S2O32-:
Moles = concentration x volume
Moles = 0.2 M x 0.0322 L
Moles = 0.00644 moles
Therefore, the number of moles of S2O32- that react in the titration is 0.00644 moles.
2) To calculate how many moles of I2 react with this amount of S2O3, we need to use the balanced chemical equation of the reaction between S2O32- and I2.
The balanced equation is:
2S2O32- + I2 -> S4O62- + 2I-
From the equation, we can see that 2 moles of S2O32- react with 1 mole of I2.
So, the moles of I2 = 0.00644 moles x (1 mole I2 / 2 moles S2O32-)
Moles of I2 = 0.00322 moles
Therefore, the number of moles of I2 that react with this amount of S2O3 is 0.00322 moles.
3) To calculate how many Cu2+ ions are needed to liberate this amount of I2, we need to use the balanced chemical equation of the reaction between I2 and Cu2+.
The balanced equation is:
2I- + Cu2+ -> CuI + I2
From the equation, we can see that 2 moles of I2 react with 1 mole of Cu2+.
So, the moles of Cu2+ = 0.00322 moles x (1 mole Cu2+ / 2 moles I2)
Moles of Cu2+ = 0.00161 moles
Since the number of moles of Cu2+ ions is the same as the number of moles of Cu2+ ions in the 25cm3 aliquot of "coin solution," we can also say that there are 0.00161 moles of Cu2+ ions in the 25cm3 aliquot of "coin solution."
To find the number of moles of Cu2+ ions in the 250cm3 of "coin solution," we can use the equation:
Moles of Cu2+ ions in 250cm3 = (0.00161 moles / 25 cm3) x 250 cm3
Moles of Cu2+ ions in 250cm3 = 0.01024 moles
Therefore, there are 0.01024 moles of Cu2+ ions in the 250cm3 of "coin solution."
4) To calculate the number of grams of copper in this "coin solution," we need to use the molar mass of copper (Cu).
The molar mass of copper (Cu) is 63.5 g/mol.
Mass of copper = Moles of Cu2+ ions x molar mass of Cu
Mass of copper = 0.01024 moles x 63.5 g/mol
Mass of copper = 0.65024 grams
Therefore, there are 0.65024 grams of copper in this "coin solution."
To answer these questions, we need to follow a step-by-step approach. Let's address each question one by one:
1) Calculate the number of moles of S2O32- which react in the titration:
We are given the molarity of sodium thiosulphate as 0.2M and the volume used in the titration as 32.2 mL. To calculate the number of moles (n) of S2O32-, we can use the formula:
n = Molarity × Volume (in liters)
Here, volume should be converted to liters:
32.2 mL ÷ 1000 = 0.0322 L
Calculate the moles:
n = 0.2 M × 0.0322 L
2) Calculate how many moles of I2 react with this amount of S2O3:
The balanced equation for the reaction between S2O32- and I2 is:
2 S2O32- + I2 → S4O62- + 2 I-
From the balanced equation, we can see that the stoichiometric ratio between S2O32- and I2 is 2:1. Therefore, the number of moles of I2 will be half of the moles of S2O32-.
3) How many Cu2+ ions are needed to liberate this amount of I2? Use this answer as the number of moles of Cu2+ ions in your 25 cm3 aliquot of "coin solution". How many moles of Cu2+ ions were in the 250 cm3 of "coin solution"?
This question involves a redox reaction where Cu2+ ions are involved. We need additional information to answer this question. It is not provided in your initial question.
4) Knowing that Ar(Cu) = 63.5, calculate the number of grams of copper in this "coin solution":
To determine the number of grams of copper in the "coin solution," we need to know the concentration of Cu2+ ions in the solution. However, it is not provided in your initial question.
Once you provide the missing information, I will be able to proceed with calculating the moles of Cu2+ ions and eventually the number of grams of copper in the "coin solution."