Answer:
1. 3.70 g Na₂CO₃·10H₂O
2. 50.0 mL of the first solution
Explanation:
1. Prepare the solution
(a) Calculate the molar mass of Na₂CO₃·10H₂O

The molar mass of Na₂CO₃·10H₂O is 286.15 g/mol.
(b) Calculate the moles of Na₂CO₃·10H₂O

(c) Calculate the mass of Na₂CO₃·10H₂O

2. Dilute the solution
We can use the dilution formula to calculate the volume needed.
V₁c₁ = V₂c₂
Data:
V₁ = ?; c₁ = 0.0500 mol·L⁻¹
V₂ = 100 mL; c₂ = 0.0250 mol·L⁻¹
Calculation:

The question is incomplete, complete question is;
A solution of
is added dropwise to a solution that contains
of
and
and
.
What concentration of
is need to initiate precipitation? Neglect any volume changes during the addition.
value 
value 
What concentration of
is need to initiate precipitation of the first ion.
Answer:
Cadmium carbonate will precipitate out first.
Concentration of
is need to initiate precipitation of the cadmium (II) ion is
.
Explanation:
1) 
The expression of an solubility product of iron(II) carbonate :
![K_{sp}=[Fe^{2+}][CO_3^{2-}]](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BFe%5E%7B2%2B%7D%5D%5BCO_3%5E%7B2-%7D%5D)
![2.10\times 10^{-11}=0.58\times 10^{-2} M\times [CO_3^{2-}]](https://tex.z-dn.net/?f=2.10%5Ctimes%2010%5E%7B-11%7D%3D0.58%5Ctimes%2010%5E%7B-2%7D%20M%5Ctimes%20%5BCO_3%5E%7B2-%7D%5D)
![[CO_3^{2-}]=\frac{2.10\times 10^{-11}}{1.15\times 10^{-2} M}](https://tex.z-dn.net/?f=%5BCO_3%5E%7B2-%7D%5D%3D%5Cfrac%7B2.10%5Ctimes%2010%5E%7B-11%7D%7D%7B1.15%5Ctimes%2010%5E%7B-2%7D%20M%7D)
![[CO_3^{2-}]=1.826\times 10^{-9}M](https://tex.z-dn.net/?f=%5BCO_3%5E%7B2-%7D%5D%3D1.826%5Ctimes%2010%5E%7B-9%7DM)
2) 
The expression of an solubility product of cadmium(II) carbonate :
![K_{sp}=[Cd^{2+}][CO_3^{2-}]](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BCd%5E%7B2%2B%7D%5D%5BCO_3%5E%7B2-%7D%5D)
![1.80\times 10^{-14}=0.58\times 10^{-2} M\times [CO_3^{2-}]](https://tex.z-dn.net/?f=1.80%5Ctimes%2010%5E%7B-14%7D%3D0.58%5Ctimes%2010%5E%7B-2%7D%20M%5Ctimes%20%5BCO_3%5E%7B2-%7D%5D)
![[CO_3^{2-}]=\frac{1.80\times 10^{-14}}{0.58\times 10^{-2} M}](https://tex.z-dn.net/?f=%5BCO_3%5E%7B2-%7D%5D%3D%5Cfrac%7B1.80%5Ctimes%2010%5E%7B-14%7D%7D%7B0.58%5Ctimes%2010%5E%7B-2%7D%20M%7D)
![[CO_3^{2-}]=3.103\times 10^{-12} M](https://tex.z-dn.net/?f=%5BCO_3%5E%7B2-%7D%5D%3D3.103%5Ctimes%2010%5E%7B-12%7D%20M)
On comparing the concentrations of carbonate ions for both metallic ions, we can see that concentration to precipitate out the cadmium (II) carbonate from the solution is less than concentration to precipitate out the iron (II) carbonate from the solution.
So, cadmium carbonate will precipitate out first.
And the concentration of carbonate ions to start the precipitation of cadmium carbonate we will need concentration of carbonate ions greater than the
concentration.
Answer:
as you move away from a planet the gravitational force gets weaker. just think, if you get close towards a sun then the gravitational force will be stronger.
Answer:
Investigation B, Step 2
Explanation:
The <em>colour change</em> is a good indication of a <em>chemical change</em>. The sugar molecules were most likely changing into something else.
Investigation A, Step 1. <em>Wron</em>g. The dissolving of salt is a <em>physica</em>l process.
Investigation A, Step 2. <em>Wrong</em>. You simply boiled off the water (a <em>physical</em> process) and recovered the salt.
Investigation B, Step 1. <em>Wrong</em>. The dissolving of sugar is a <em>physical</em> process.