A is obviously out because it leads to a volume of 125.0 milliliters of the new solution and gives you a lower concentration than you were aiming for.
D is out because you are adding 75 milliliters of the stock solution, so your concentration would be too high. You only need 25.0 milometers of stock solution per 100 milliliters of the new solution.
C is also out because it leads to 50.0 milliliters stock solution per 100 milliliters of the new solution and hence the wrong concentration.
B is by default the correct answer. It also details the correct technique. First you add the stock solution (This you know from your calculations to be 25 milliliters.) then you add the water up to the volume you needed. (Because the calculations only tell you the total volume of water not what you need to add) You also add the water last so you can rinse the neck of the flask to make sure you also get all the stock solution residue into the stock solution.
I would add the final step of stirring, but B is the only answer that can be correct.
To find average atomic mass you multiply the mass of each isotope by its percentage, and then add the values up.
35 * 0.90 + 37 * 0.08 + 38 * 0.02 = 35.22
Average atomic mass closest to 35.22 amu.
Answer:
Explanation:
Percent composition by element
Element Symbol # of Atoms
Chlorine Cl 2
Calcium Ca 1
Oxygen O 6
Answer:
Fe(s) → Fe²⁺(aq) + 2e⁻ OXIDATION
Mg²⁺(aq) + 2e⁻ → Mg(s) REDUCTION
Explanation:
The redox reaction is: MgCl₂(aq) + Fe(s) → FeCl₂(aq) + Mg(s)
We need to know that elements in ground state have 0 as the oxidation state.
Iron in the reactants, and Mg in the products
In the magnessium chloride, the Mg acts with+2, so the oxidation state has decreased → REDUCTION
In the iron(II) chloride, the Fe acts with +2, so the oxidation statehas increased → OXIDATION
The half reactions are:
Fe(s) → Fe²⁺(aq) + 2e⁻ OXIDATION
Mg²⁺(aq) + 2e⁻ → Mg(s) REDUCTION
Answer:
63.01284 g/mol
Explanation:
This compound is also known as Nitric Acid.
Convert grams HNO3 to moles or moles HNO3 to grams
Molecular weight calculation:
1.00794 + 14.0067 + 15.9994*3
Percent composition by element
Element Symbol Atomic Mass # of Atoms Mass Percent
Hydrogen H 1.00794 1 1.600%
Nitrogen N 14.0067 1 22.228%
Oxygen O 15.9994 3 76.172%
