Answer:
a) pH = 13.176
b) pH = 13
c) pH = 12.574
d) pH = 7.0
e) pH = 1.46
f) pH = 1.21
Explanation:
HBr + NaOH ↔ NaBr + H2O
∴ equivalent point:
⇒ mol acid = mol base
⇒ (Va)*(0.150mol/L) = (0.025L)*(0.150mol/L)
⇒ Va = 0.025 L
a) before addition acid:
⇒ <em>C </em>NaOH = 0.150 M
⇒ [ OH- ] = 0.150 M
⇒ pOH = - Log ( 0.150 )
⇒ pOH = 0.824
⇒ pH = 14 - pOH
⇒ pH = 13.176
b) after addition 5mL HBr:
⇒ <em>C </em>NaOH = (( 0.025)*(0.150) - (0.005)*(0.150)) / (0.025 + 0.005) = 0.1 M
⇒ <em>C </em>HBr = (0.005)*(0.150) / ( 0.03 ) = 0.025 M
⇒ [ OH- ] = 0.1 M
⇒ pOH = 1
⇒ pH = 13
c) after addition 15mL HBr:
⇒ <em>C </em>NaOH = ((0.025)*(0.150) - (0.015)*(0.150 ))/(0.04) = 0.0375 M
⇒ <em>C </em>HBr = ((0.015)*(0.150))/(0.04) = 0.0563 M
⇒ [ OH- ] = 0.0375 M
⇒ pOH = 1.426
⇒ pH = 12.574
d) after addition 25mL HBr:
equivalent point:
⇒ [ OH- ] = [ H3O+ ]
⇒ Kw = 1 E-14 = [ H3O+ ] * [ OH- ] = [ H3O+ ]²
⇒ [ H3O+ ] = 1 E-7
⇒ pH = 7.0
d) after addition 40mL HBr:
⇒ <em>C</em> HBr = ((0.04)*(0.150) - (0.025)*(0.150)) / (0.04 + 0.025) = 0.035 M
⇒ [ H3O+ ] = 0.035 M
⇒ pH = 1.46
d) after addition 60mL HBr:
⇒ <em>C</em> HBr = ((0.06)*(0.150) - (0.025)*(0.150)) / (0.06+0.025) = 0.062 M
⇒ [ H3O+ ] = 0.062 M
⇒ pH = 1.21
Answer:
The molarity is 0,4M
Explanation:
The molartity is moles of compound (in this case KCl) in 1 liter of solution :
2 L----------0,8 moles KCl
1 L-----------x= (1L x0,8 moles KCl)/2L= 0,4 moles KCl--> 0,4M
H₂S
<h3>Further explanation</h3>
Given
ΔH fusion and ΔH vaporization of different substances
Required
The substance absorbs 58.16 kJ of energy when 3.11 mol vaporizes
Solution
We can use the formula :
Q=heat/energy absorbed
n = moles
The heat absorbed : 58.16 kJ
moles = 3.11
so ΔH vaporization :
The correct substance which has ΔH vaporization = 18.7 kj / mol is H₂S
(H₂S from the data above has ΔH fusion = 2.37 kj / mol and ΔH vaporization = 18.7 kj / mol)
Answer:
There are 140.9 grams in 2.393*10²⁴ aotms of Cl.
Explanation:
Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023*10²³ particles per mole. Avogadro's number represents a quantity without an associated physical dimension, so it is considered a pure number that allows describing a physical characteristic without an explicit dimension or unit of expression. Avogadro's number applies to any substance.
Then you can apply the following rule of three: if 6.023*10²³ atoms are contained in 1 mole of the compound, 2.393*10²⁴ atoms are contained in how many moles?
amount of moles= 3.973
If the molar mass of Cl is 35.453 
, then the amount of mass that contains 3.973 moles can be calculated as:
3.973 moles*35.453 = 140.85 grams ≅ 140.9 grams
<u><em>There are 140.9 grams in 2.393*10²⁴ aotms of Cl.</em></u>
Answer: 1.037M
Explanation:
Since the rate constant unit is per seconds, therefore it is a first order reaction.
First order reaction equation is given as
InA= -kt +InAo
Where,Ao is the initial concentration of reactant =0.600M
A is the concentration of reactant at a specifies time t=3×60=180s
and k is the rate constant
InA = -6.50×10^-3 ×180 +In(0.6)
InA = -1.17 + 0.5108
InA= -1.680
A = e-1.680
A= 1.037M
Therefore the concentration after 3minutes is 1.037M
