Answer:
315mL
Explanation:
Data obtained from the question include the following:
Molarity of stock solution (M1) = 0.135 M
Volume of stock solution needed (V1) =?
Molarity of diluted solution (M2) = 0.0851 M
Volume of diluted solution (V2) = 500mL
The volume of the stock solution needed can be obtain as follow:
M1V1 = M2V2
0.135 x V1 = 0.0851 x 500
Divide both side by 0.135
V1 = (0.0851 x 500) / 0.135
V1 = 315mL
Therefore, the volume of the stock solution needed is 315mL
Answer:
Yes, a chemical change occurs.
Explanation:

CaSO4 is insoluble in the water, so a chemical reaction or chemical change occurs.
Answer:
A. To focus on only those ions that form the precipitate
Explanation:
Net ionic equations cancel out the ions that appear on both sides of the reaction because they essentially don't participate in the reaction. This is very useful when dealing with redox reactions because are complicated enough without spectator ions being in the way, so they help focus on those ions that actually form the precipitate.
Key Terms
- Spectator Ions: an ion that does not take part in the chemical reaction.
- Net ionic equations: a equation where ions that appear on both sides are canceled out.
- Redox reaction: an oxidation-reduction reaction.
Answer: Sodium
Explanation: The sodium has only one electron at the outer layer.
Hope this helps! :)