Answer: There are few simple rules to follow.
(1) The atomic number is equal to the number of protons.
Z
= number of protons
(2) In neutrally charged elements, the number of electrons is the same as the number of protons.
Z
= number of protons = number of electrons (no charge)
Otherwise, positive charge means that the element lost an electron and negative charge means it gained an electron.
(3) The atomic mass is equal to the sum of the number of protons and number of neutrons.
A
= number of protons + number neutrons
or
A
=
Z
+ number neutrons
So if you say that
Z
= 20 and
A
= 40, then
A
=
Z
+ number neutrons
40 = 20 + number of neutrons
40 - 20 = number of neutrons
Therefore,
number of neutrons = 20
Explanation:
Answer:
0.0457 M
Explanation:
The reaction that takes place is:
- 2HBr + Ca(OH)₂ → CaBr₂ + 2H₂O
First we<u> calculate how many moles of acid reacted</u>, using the <em>HBr solution's concentration and volume</em>:
- Molarity = Moles / Volume
- Molarity * Volume = Moles
- 0.112 M * 12.4 mL = 1.389 mmol HBr
Now we <u>convert HBr moles to Ca(OH)₂ moles</u>, using the stoichiometric ratio:
- 1.389 mmol HBr * = 0.6944 mmol Ca(OH)₂
Finally we <u>calculate the molarity of the Ca(OH)₂ solution</u>, using the <em>given volume and calculated moles</em>:
- 0.6944 mmol Ca(OH)₂ / 15.2 mL = 0.0457 M
Based on the standards of units conversion, to convert from micrometer to meter, we multiply by 10^-6.
Since we there is a square (10^2) to consider, then to convert from micrometer squared to meter squared, we will multiply by (10^-6)^2 as follows:
1.5 <span>μm2 = 1.5 x (10^-6)^2 = 1.5 x 10^-12 meter sqaures</span>
Answer:
The interaction reaction of calcium oxide and water leads to the formation of calcium hydroxide, this reaction is exothermic, which indicates that energy is released.
CaO(s) + H2O ⇒ Ca(OH)2
Explanation:
Calcium oxide reacts violently with water, causing it to reach 90 C. It then forms calcium hydroxide, also called slaked lime. It is heated because it releases energy in the form of heat, because the new substance formed (slaked lime) has less internal energy than the original and this is released in the form of heat. As a general rule, acid and base solutions are exothermic.