Answer:
<em>the <u>valency of an element</u> is its combining capacity that is the number of electrons it requires to lose, gain or share in order to become neutral.</em>
[ An element can become neutral if it completes it's octet. That is if an element has 8 electrons in it'd outermost shell then it is considered neutral ]
- The valence of Magnesium is 2 because it requires to lose 2 electrons to become neutral.
- whereas, the valence of Oxygen is 2 because it needs to gain 2 electrons to become stable.
Hence they both have the same valence.
One may say that oxygen's valence is -2 while that of Magnesium is + 2. It's meaning is still the same but "-" sign indicates that oxygen will be gaining electrons in the process of becoming stable.
a balanced chemical equation occurs when the number of the atoms involved in the reactants side is equal to the number of atoms in the products side.
We calculate for the amount of chromium metal in the reactant by,
= 350 x (mass of Cr2/mass of Cr2O3)
= 350 x (104/152)
= 239.47 grams
The amount of Cr metal in the product is only 213.2 grams. Thus, the percent yield.
percent yield = (213.2 grams/239.47) x 100%
= 89%
Explanation:
1 mole of a gas has 22.4 L of volume at STP. Therefore, 0.5 mol of H2 has 0.5 x 6.022 x 1023 = 3.011 x 1023 molecules. Hence, the number of moles, molecules and atoms present in 11.2 liters of H2 at STP are 0.5 , 3.011 x 1023 and 6.022 x 1023 respectively.
Answer: Charles's law, Avogadro's law and Boyle's law.
Justification:
Boyle's law states that at constant temperature PV = constant
Charles law states that at constant pressure V/T = constant
Avogadro's law states that at constant pressure ant temperature, equal volume of gases contain equal number of moles: V/n = constant
Ideal gas law states PV/nT = constant => PV = nT*constant = PV = nTR
