<span> First you need to know how many isotopes there are of silicon, and its average atomic units (look at periodic table). Then make up a system of equations to solve for it. Theres 3 stable silicon isotopes (28, 29, 30) so you will need to have 3 equations. You must be given the percent abundance of at least one of the isotopes to solve because here I can only see 2 equations (numbered down below) set x = percent abundance of si-28 y = percent abundance of si-29 z = percent abundance of si-30 since all of silicon atoms account for 100% of all silicon: x + y + z = 100% = 1 therefore: 1) x = 1 - y - z You also have 2) 28x + 29y + 30z = average atomic mass you can substitute x so that equation becomes: 28 (1 - y - z) + 29y + 30z = average atomic mass See how you have 2 variables here? You cant go on until you know the value of one isotope already or you have given a clue which you can derive the third equation</span>
Answer:
Sun and the stars, nothing humans don't use fusion at all
Explanation:
23.01 g of zinc (Zn)
Explanation:
We have the following chemical reaction:
3 Zn + 2 H₃PO₄ = 3 H₂ + Zn₃(PO₄)₂
number of moles = mass / molar weight
number of moles of phosphoric acid = 23.1 / 98 = 0.236 moles
Taking in account the chemical reaction, we devise the following reasoning:
if 2 moles of H₃PO₄ are reacting with 3 moles of Zn
then 0.236 moles of H₃PO₄ are reacting with X moles of Zn
X = (0.236 × 3) / 2 = 0.354 moles of Zn
mass = number of moles × molar weight
mass of Zn = 0.354 × 65 = 23.01 g
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number of moles
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