Answer:
Explanation:
A. The charge on an element is determined by the differences between the number of protons and electrons in an atom.
An atom will have no charges if the number of protons and electrons are the same.
- When an atom loses or gains electrons, the number of electrons will either decrease or increase
- if the number of electrons is more than the number of protons, the excess electrons is the charge on the atom. And this makes the atom become a negatively charged ion.
- if the number of electrons is lesser than the number of protons, the deficient electrons makes the atom a positively charged ion. The number of electrons by which the atom is deficient makes the atom a positively charged ion.
Charge = number of protons - number of electrons
B. Electrons form the charges they do because with the charge, they become stable like the noble gases.
The desire of every atom is to have stable electronic configuration like those of the noble gases.
A potassium atom with a configuration 2 8 8 1 will prefer to lose an electron to become an Argon atom making the ion stable.
1.66 M is the concentration of the chemist's working solution.
<h3>What is molarity?</h3>
Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per litres of a solution. Molarity is also known as the molar concentration of a solution.
In this case, we have a solution of Zn(NO₃)₂.
The chemist wants to prepare a dilute solution of this reactant.
The stock solution of the nitrate has a concentration of 4.93 M, and he wants to prepare 620 mL of a more dilute concentration of the same solution. He adds 210 mL of the stock and completes it with water until it reaches 620 mL.
We want to know the concentration of this diluted solution.
As we are working with the same solution, we can assume that the moles of the stock solution will be conserved in the diluted solution so:
= 
(1)
and we also know that:
n = M x 
If we replace this expression in (1) we have:
x 
= 
x
Where 1, would be the stock solution and 2, the solution we want to prepare.
So, we already know the concentration and volume used of the stock solution and the desired volume of the diluted one, therefore, all we have to do is replace the given data in (2) and solve for the concentration which is :
4.93 x 210 = 620 x
= 1.66 M
This is the concentration of the solution prepared.
Learn more about molarity here:
brainly.com/question/19517011
#SPJ1
Answer:
1.8 moles of NaCl must be produced.
Explanation:
Based on the reaction:
HCl + NaOH → NaCl + H2O
<em>1 mol of HCl reacts with 1 mol of NaOH to produce 1mol of NaCl</em>
<em />
To solve this question we must find, as first, the <em>limiting reactant:</em>
<em />
1.8 moles of HCl will need 1.8 moles of NaOH for a complete reaction (Ratio of reaction 1:1). As there are 3.3 moles of NaOH,
<em>HCl is limiting reactant</em>
<em />
When the 1.8 moles of HCl react completely,
1.8 moles of NaCl must be produced because 1 mole of HCl produce 1 mole of NaCl
Yes it could, but you'd have to set up the process very carefully.
I see two major challenges right away:
1). Displacement of water would not be a wise method, since rock salt
is soluble (dissolves) in water. So as soon as you start lowering it into
your graduated cylinder full of water, its volume would immediately start
to decrease. If you lowered it slowly enough, you might even measure
a volume close to zero, and when you pulled the string back out of the
water, there might be nothing left on the end of it.
So you would have to choose some other fluid besides water ... one in
which rock salt doesn't dissolve. I don't know right now what that could
be. You'd have to shop around and find one.
2). Whatever fluid you did choose, it would also have to be less dense
than rock salt. If it's more dense, then the rock salt just floats in it, and
never goes all the way under. If that happens, then you have a tough
time measuring the total volume of the lump.
So the displacement method could perhaps be used, in principle, but
it would not be easy.
Answer:
1. filtration and evaporation
2. i) water is added to the sand and salt mixture
ii) then the mixture is filtrated and so the sand and the salt water was seperated
iii) the salt water is heated with the help of burner until the water gets evaporated
iv) after the water gets evaporated, the salt is remained in the container
3. observation:
- on adding water to the mixture, the salt is completely dissolved in the water
- when filtrated the sand is seperated from the salt water
- now the salt water when heated with the burner until the evaporation, the water is evaporated
- the salt is precipitated and remained in the container
4. cautions:
- while using the burner, we should be cautious with fire
- the container that is heated should be holded with the help of a cloth to avoid heat
