Answer:
C
Explanation:
energy is measures the capacity to do work.
Answer:
The element is Magnesium.
Explanation:
On the periodic table, elements are arranged based on atomic number and chemical similarity.
- A group on the periodic table is a vertical column that places elements with very similar chemical characteristics together. For instance, the elements in group 18 are all gases (this group is named the Noble Gases group).
- A period on the periodic table is a horizontal row that places elements that show periodic trends together. They also have very similar characteristics (same amount of subshells that house electrons).
If we look at the periodic table, we will notice that there are eighteen groups and seven periods. And, we can also see that the groups are vertical while the periods are horizontal.
Therefore, if we count two across and three down, we will see the element Mg - atomic number 12. Mg is the element <em>symbol</em>, not the name, so we can look and see that the name of the element is Magnesium.
Answer:
(a) oxygen
(b) 154g (to 3sf)
(c) 79.9% (to 3sf)
Explanation:
mass (g) = moles × Mr/Ar
note: eqn means chemical equation
(a)
moles of P = 84.1 ÷ 30.973 = 2.7152 moles
moles of O2 = 85÷2(16) = 2.65625 moles
Assuming all the moles of P is used up,
moles of O2 / moles of phosphorus = 5/4 (according to balanced chemical eqn)
moles of O2 required = 5/4 × 2.7152moles = 3.394 moles (more than supplied which is 2.65625moles)
therefore there is insufficient moles of O2 and the limiting reactant is oxygen.
(b)
moles of P2O5 produced
= 2/5 (according to eqn) × 2.7152
= 1.08608moles
mass of P2O5 produced
= 1.08608 × [ 2(30.973) + 5(16) ]
= 154.164g
= approx. 154g to 3 sig. fig.
(c)
% yield = actual/theoretical yield × 100%
= 123/154 × 100%
= 79.870%
= approx. 79.9% (to 3sf)