Answer=4
A solution is a mixture of substances
We know that the number of moles HCl in 14.3mL of 0.1M HCl can be found by multiplying the volume (in L) by the concentration (in M).
(0.0143L HCl)x(0.1M HCl)=0.00143 moles HCl
Since HCl reacts with KOH in a one to one molar ratio (KOH+HCl⇒H₂O+KCl), the number of moles HCl used to neutralize KOH is the number of moles KOH. Therefore the 25mL solution had to contain 0.00143mol KOH.
To find the mass of KOH in the original mixture you have to divide the number of moles of KOH by the 0.025L to find the molarity of the KOH solution..
(0.00143mol KOH)/(0.025L)=0.0572M KOH
Since the morality does not change when you take some of the solution away, we know that the 250mL solution also had a molarity of 0.0572. That being said you can find the number of moles the mixture had by multiplying 0.0572M KOH by 0.250L to get the number of moles of KOH.
(0.0572M KOH)x(0.250L)=0.0143mol KOH
Now you can find the mass of the KOH by multiplying it by its molar mass of 56.1g/mol.
0.0143molx56.1g/mol=0.802g KOH
Finally you can calulate the percent KOH of the original mixture by dividing the mass of the KOH by 5g.
0.802g/5g=0.1604
the original mixture was 16% KOH
I hope this helps.
Answer:
number of dozens = 4.35834 * 10^21 dozens
Explanation:
A dozen contains 12 atoms. To know the number of dozens containing
5.23 * 10^22 atoms, all we have to do is cross multiplication as follows:
1 dozen ...........> 12 atoms
?? dozens ......> <span>5.23 * 10^22
number of dozens = (</span><span>5.23 * 10^22 *1) / (12)
number of dozens = 4.35834 * 10^21 dozens
Hope this helps :)</span>
Answer:
The answer to your question is pH = 2.2
Explanation:
Data
pH = ?
moles of HCl = 0.927
volume = 150 l
Process
1.- Calculate the Molar concentration of HCl
Molarity = moles / volume (L)
Molarity = 0.927 / 150
= 0.00618
2.- Calculate the pH
pH = -log [HCl]
Substitution
pH = -log [0.00618]
Result
pH = 2.2
Answer:
Atomic number of this isotope = 77
Explanation:
Given that,
Mass number = 193
No of neutrons = 116
We need to find the atomic no of this isotope.
We know that,
Atomic mass = No of protons + No. of neutrons
Also, atomic no = no of protons
So,
Atomic mass = atomic no + No. of neutrons
⇒ Atomic no = Atomic mass - no of neutrons
Atomic no = 193 - 116
Atomic no = 77
Hence, 77 is the atomic no of the isotope.
