Answer:
73.2g
Explanation:
The reaction expression is given as:
P₄ + 6Cl₂ → 4PCl₃
Given parameters:
Volume of chlorine gas = 79.2L
Unknown:
Mass of Phosphorus needed = ?
Solution:
To solve this problem, let us find the number of moles of the chlorine gas.
Since the condition of the reaction is at STP;
22.4L of gas is contained in 1 mole
79.2L of chlorine gas will contain 
= 3.54mole
From the reaction expression;
6 moles of chlorine gas will react with 1 mole of P₄
3.54 mole of chlorine gas will completely react with 
= 0.59mole of P₄
Mass of P₄ = number of moles x molar mass
Molar mass of P₄ = 4 x 31 = 124g/mol
Mass of P₄ = 0.59 x 124 = 73.2g
Time taken for star to reach Earth = 7.5 years
<h3>Further explanation</h3>
Given
7.5 light years(distance Earth-star)
Required
Time taken
Solution
Speed of light=v = 3 x 10⁸ m/s
1 light years = 9.461 × 10¹⁵ m= distance(d)
So time taken for 1 light years :
time(t) = distance(d) : speed(v)
t = 9.461 × 10¹⁵ m : 3 x 10⁸ m/s
t = 3.154 x 10⁷ s = 1 years
So for 7.5 light years, time taken = 7.5 years
Answer:
359 grams FeO
Explanation:
To find how many grams FeO are produced, you need to use the moles of Fe, convert it to moles of FeO (using the mole-to-mole ratio from the equation), then convert the moles of FeO to grams (using the molar mass from the periodic table).
2 Fe + O₂ --> 2 FeO
Molar Mass (FeO) = 55.845 g/mol + 16.00 g/mol
Molar Mass (FeO) = 71.845 g/mol
5.00 moles Fe 2 moles FeO 71.845 grams
---------------------- x ------------------------ x ---------------------- = 359 grams FeO
2 moles Fe 1 mole FeO
Answer:
They exist at specific energy levels
Explanation:
