Answer:
3.53 g
Explanation:
To convert from atoms to moles, you need to know Avogadro's number. Avogadro's number (6.022 × 10²³) is how many atoms there are in one mole of a substance. Use this to convert.
(1.97 × 10²² atoms) ÷ (6.022 × 10²³ atoms/mol) = 0.0327 mol
Now that you have moles, use the molar mass to convert to grams.
(0.0327 mol) × (107.87 g/mol) = 3.53 g
Atomic mass silicon = 28.085 u
1 mol Si ---------------- 28.085 g
? ------------------------ 245 g
245 x 1 / 28.085 =><span> 8.72 mol</span>
<span>answer A</span>
The change in pH is calculated by:
pOH = Protein kinase B + log [NH4+]/ [NH3]
Protein kinase B of ammonia = 4.74
initial potential of oxygen hydroxide= 4.74 + log 0.100/0.100 = 4.74
pH = 14 - 4.74=9.26
moles NH4+ = moles NH3 = 0.100 L x 0.100 M = 0.0100
moles H+ added = 3.00 x 10^-3 L x 0.100 M=0.000300
NH3 + H+ = NH4+
moles NH3 = 0.0100 - 0.000300=0.00970
moles NH4+ = 0.0100 + 0.000300=0.0103
pOH = 4.74 + log 0.0103/ 0.00970= 4.77
oH = 14 - 4.77 = 9.23
the change is = 9.26 - 9.23 =0.03
Answer:
b. HCOOH/ NaHCOO.
Explanation:
A buffer system may be formed in one of two forms:
- A weak acid with its conjugate base.
- A weak base with its conjugate acid.
Chose the pairs below that you could use to make a buffered solution.
a. HCI/NaOH. NO. HCl is a strong acid and NaOH is a strong base.
b. HCOOH/ NaHCOO. YES. HCOOH is a weak acid and HCOO⁻ (coming from NaHCOO) is its conjugate base.
c. HNO₂/H₂SO₃. NO. Both are acids and they are unrelated to each other.
d. NaNO₃/ HNO₃. NO. HNO₃ is a strong acid.
