So I have to find the % by mass of an unknown metal that reacted with HCl to create MCl2 (with the M being unknown). Then I need to determine identity of the missing metal.
I know that the final mass of the compound MCl2 is 12.47g and that the original mass of the metal M before the reactions was 5.65g.
Also, I'm told the reaction went to 100% completion.
I'm stuck because I'm not sure if I can assume that since all of the metal reacted that I can divide 5.65g by 12.47g to find the % by mass of the unknown metal in the compound.
Can I do that or are there other steps that I need to do first?
If so, how? I can't think of how else to use those two values other than subtracting or dividing them to find the percentages since I don't have the molar mass of the compound.
Yes, %M = (5.65/12.47)*100 = ? about 45% but you need a more accurate number than that.
Then what do you do to identify the metal. I will use estimates BUT you must get accurate numbers yourself.
%Cl then must be 100%-45.?% = about 55%. Be sure and get good numbers to at least 3 places.
Here is how you would do it IF you had the atomic mass of the metal. You don't so we will call it x.
mols M = about (45/x) = y
mols Cl = about (55/35.45) = about 1.5. You KNOW the formula is MCl2; therefore, that 1.5 number for the mols Cl must be twice the y number so y must be about 0.75. That means x = about (45/0.75) = about 60 or so
You can look that up on the periodic table. I stress the accuracy of your numbers because it will be difficult to know the difference between two possible elements. The metal is between Fe and Cu on the periodic table.
Thanks for the clarification and confirming my assumption. I'll be sure to use accurate values in the calculation.
To find the percent by mass of the unknown metal in the compound MCl2, you need to follow these steps:
1. Calculate the mass of chlorine (Cl) present in the compound MCl2.
- Since the compound MCl2 has a mass of 12.47g, and each mole of Cl has a molar mass of 35.45g/mol, you can calculate the moles of Cl using the mole-to-mass ratio: Moles of Cl = Mass of compound (g) / Molar mass of Cl (g/mol)
- Moles of Cl = 12.47g / 35.45g/mol
2. Calculate the moles of M in the compound MCl2.
- Since MCl2 has a 1:2 stoichiometric ratio with respect to M and Cl, the moles of M will be half the moles of Cl.
- Moles of M = Moles of Cl / 2
3. Calculate the percent by mass of M in the compound MCl2.
- The percent by mass is calculated as the mass of M divided by the total mass of the compound, multiplied by 100%.
- Percent by mass of M = (Moles of M × Molar mass of M) / Mass of compound (g) × 100%
Therefore, to find the percent by mass of the unknown metal (M) in the compound MCl2, you need the molar mass of M. If you have the molar mass of M, you can proceed with the calculations outlined above. If you don't have the molar mass of M, you will need additional information or experimental data to determine the identity of the missing metal.
To find the percentage by mass of the unknown metal in the compound MCl2, you need to follow a few steps:
1. Start by calculating the mass of chlorine in MCl2. Since MCl2 is a binary compound, the mass of chlorine can be determined by subtracting the mass of the metal from the total mass of the compound:
Mass of chlorine = Total mass of MCl2 - Mass of metal M
In this case, the total mass of MCl2 is given as 12.47g, and the mass of metal M is given as 5.65g. So, you can calculate:
Mass of chlorine = 12.47g - 5.65g
2. Once you have the mass of chlorine, you can determine the mass percentage of the metal in the compound. To do this, divide the mass of the metal M by the total mass of MCl2 and multiply by 100:
Percentage by mass of metal M = (Mass of metal M / Total mass of MCl2) x 100
Plugging in the values, you get:
Percentage by mass of metal M = (5.65g / 12.47g) x 100
Performing the calculation:
Percentage by mass of metal M = 45.35%
Now, to determine the identity of the missing metal, you need additional information. Since you don't have the molar mass of the compound, you can't directly calculate the molar mass of the metal. However, you can compare the mass percentage obtained with the atomic masses of different metals to find a suitable match. Look for a metal that has a molar mass close to the calculated mass percentage value of 45.35%.
Keep in mind that this method assumes the reaction went to 100% completion, meaning all of the metal reacted. If the reaction did not go to completion, there might be a slightly different percentage by mass of the metal in the compound.