Answer:
18.1 g
Explanation:
You know that the atomic weight of phosphorus is equal to
30.794 u
, where
u
represent the unified atomic mass unit.
The unified atomic mass unit is equivalent to
1 g/mol
, but let's take the long road and prove that identity.
Now, the unified atomic mass unit is defined as
1
12
th
of the mass of a single unbound carbon-12 atom in its ground state and is equivalent to
1 u
=
1.660539
⋅
10
−
24
g
This means that the mass of one phosphorus atom will be
30.974
u
⋅
1.660539
⋅
10
−
24
g
1
u
=
5.14335
⋅
10
−
23
g
You know that one mole of any element contains exactly
6.022
⋅
10
23
atoms of that element - this is known as Avogadro's number.
Well, if you know the mass of one phosphorus atom, you can use Avogadro's nubmer to determine what the mass of one mole of phosphorus atoms
5.14335
⋅
10
−
23
g
atom
⋅
6.022
⋅
10
23
atoms
1 mole
=
30.974 g/mol
Finally, if one mole of phosphorus atoms has a mass of
30.974 g
, then
0.585
moles will have a mass of
0.585
moles
⋅
30.974 g
1
mole
=
18.1 g
From: https://socratic.org/questions/the-atomic-weight-of-phosphorus-is-30-974-u-what-is-the-mass-of-a-phosphorus-sam
Answer: The concentration of the KOH solution is 1.01 M
Explanation:
According to neutralization law:
where,
= basicity of 
= 1
= acidity of KOH = 1
= concentration of HCl = 3.00 M
= concentration of KOH = ?
= volume of HCl = 35.3 ml
= volume of KOH = 105.0 ml
Putting the values we get:
Thus the concentration of the KOH solution is 1.01 M
Answer:
-1.71 J/K
Explanation:
To solve this problem we use the formula
ΔS = n*ΔH/T
Where n is mol, ΔH is enthalpy and T is temperature.
ΔH and T are already given by the problem, so now we calculate n:
Molar Mass C₂H₅OH = 46 g/mol
2.71 g C₂H₅OH ÷ 46g/mol = 0.0589 mol
Now we calculate ΔS:
ΔS = 0.0589 mol * −4600 J/mol / 158.7 K
ΔS = -1.71 J/K
Answer : The number of grams of calcium perchlorate is, 0.00253 grams.
Explanation :
Molar mass of calcium perchlorate = 238.9 g/mol
As, 
formula units present in 238.9 g of calcium perchlorate
So, 
formula units present in 
of calcium perchlorate
Therefore, the number of grams of calcium perchlorate is, 0.00253 grams.
