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OLga [1]
3 years ago
10

A student has a 0.00124 M HCl (aq) solution and she titrates 25.00 mL of this solution against an unknown potassium hydroxide so

lution. The acid requires 44.25 mL of base to reach the end point, what is the molarity of the KOH (aq) solution?
Chemistry
1 answer:
malfutka [58]3 years ago
5 0

Answer:

The Molarity of KOH is

7,01.10^{-4}M

Explanation:

The endpoint indicates the volume necessary to neutralize the moles of acid.

In other words, the point at which the moles of both solutions are the same.

M_{(HCl)}V_{HCl}=n\\ \\M_{(KOH)}V_{KOH}=n

we match these equations and find the concentration of KOH

M_{(HCl)}. V_{(HCl)} =M_{(KOH)} .V_{(KOH)}\\ \\M_{(KOH)}=\frac{M_{(HCl)}. V_{(HCl)}}{V_{(KOH)}} \\\\M_{(KOH) =\frac{(25mL)(0,00124m)}{(44,25mL)}\\\\

M_{(KOH)}=7,01.10^{-4}

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How many grams of sodium oxide can be produced when 55.3 g Na react with 64.3 g O2?. . Unbalanced equation: Na + O2 → Na2O. . Sh
GenaCL600 [577]
 <span>this is a limiting reagent problem. 

first, balance the equation 
4Na+ O2 ---> 2Na2O 

use both the mass of Na and mass of O2 to figure out how much possible Na2O you could make. 
start with Na and go to grams of Na2O 

55.3 gNa x (1molNa/23.0gNa) x (2 molNa2O/4 molNa) x (62.0gNa2O/1molNa2O) = 75.5 gNa2O 

do the same with O2 

64.3 gO2 x (1 molO2/32.0gO2) x (2 molNa2O/1 mol O2) x (62.0gNa2O/1molNa2O) = 249.2 g Na2O 

now you must pick the least amount of Na2O for the one that you actually get in the reaction. This is because you have to have both reacts still present for a reaction to occur. So after the Na runs out when it makes 75.5 gNa2O with O2, the reaction stops. 

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3 years ago
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Explain how chemical change differs from a physical change
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A chemical change affects on the molecular level of matter, which makes it irreversible. Combustion is a pretty good exmple. Physical changes are reversible and dont alter the formula. Hope this helped!
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3 years ago
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Why do atoms always contain the same number of electrons and protons?
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An electron is a negatively charged subatomic particle and a proton is a positively charged subatomic particle. Positive charge(s) attract negative charge(s) and vice versa. The proton and neutron stay together and attract one another to give the atom an overall charge of zero (neutral). Which is the charge of an atom. When there is an unequal number of protons and neutrons an ion is formed. If the number of protons are more than the electron, a positively charged ion called cation is formed. On the other hand, if the number of electrons are more than the protons a negatively charged ion called anion is formed.

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Marizza181 [45]

Answer:

\Delta _rH=-1124.14kJ/mol

Explanation:

Hello!

In this case, since the standard enthalpy change for a chemical reaction is stood for the enthalpy of reaction, for the given reaction:

2H_2S(g) +3O_2(g)\rightarrow 2H_2O(l) +2SO_2(g)

We set up the enthalpy of reaction considering the enthalpy of formation of each species in the reaction at the specified phase and the stoichiometric coefficient:

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In such a way, by using the NIST database, we find that:

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Thus, we plug in the enthalpies of formation to obtain:

\Delta _rH=2(-285.73kJ/mol)+2(-296.84kJ/mol)-2(-20.50kJ/mol)-3(0kJ/mol)\\\\\Delta _rH=-1124.14kJ/mol

Best regards!

8 0
3 years ago
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