Answer:
number of moles = 0.21120811
Explanation:
To find the number of moles, given the mass of the solute, we use the formula:




Label the variables with the numbers in the problem:



The first thing we have to do is find the molar mass of sodium sulfate, in order for us to use the formula for finding the number of moles:
Formula for finding the molar mass of sodium sulfate:

For the variables and what they mean are below for finding the molar mass of sodium sulfate:





Plug the numbers into the formula, to find the molar mass of sodium sulfate:











Now that we have found the molar mass, we can calculate the number of moles in the solution of sodium sulfate with the formula:








0.21120811 rounded gives you 0.2112
or if you did the problem without decimals
30 grams of sodium sulfate divided by its molecular weight – which we found to be 142 – gives us a value of 0.2113 moles.
Answer:
144 u
Explanation:
The average atomic mass of carbon is approximately 12 u.
Multiply 12 x 12:
12 x 12 = 144
The balanced reaction is 2KClO3 --> 2KCl + 3O2
We first divide the 400.0 g KClO3 by the molar mass of 122.55 g/mol to get 3.26 mol KClO3. Next, we use the coefficients: 3.26 mol KClO3 * (3 mol O2 / 2 mol KClO3) = 4.896 mol O2. Multiplying this by the molar mass of 32 g/mol gives 156.67 g O2.
Percent yield = 115.0 g / 156.67 g = 0.734 = 73.40%
Answer:
H₂Se
Explanation:
A way of estimating the acidity of a weak acid is by analizing the<em> stability of the formed anion</em>. In this case, we should find a Group 6A element that in its anionic forms (HX⁻ and X⁻²) is more stable than HS⁻ and S⁻², thus it would be more acidic in aqueous solution.
The anionic forms of Se are more stable than the forms of S, similarly to how Br⁻ is more stable than Cl⁻.