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Nonamiya [84]
2 years ago
10

What is the BEST way to determine if a chemical change has occurred?

Chemistry
1 answer:
Yuri [45]2 years ago
7 0

Answer:

2. examine the properties before and after the change

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A 250. ML sample of 0.3M HCl is partially neutralized by the addition of 100. ML of 0.25M NaOH.Find the concentration of hydroch
GuDViN [60]

Answer:- 0.143 M

Solution:- HCl and NaOH reacts in 1:1 mol ratio as shown in the below reaction:

HCl(aq)+NaOH(aq)\rightleftharpoons NaCl(aq)+H_2O(l)

Let's calculate the initial moles of HCl and the moles of NaOH added to it:

250.mL(\frac{1L}{1000mL})(\frac{0.3molHCl}{1L})

= 0.075 mol HCl

100.mL(\frac{1L}{1000mL})(\frac{0.25molNaOH}{1L})

= 0.025 mol NaOH

Since they react in 1:1 mol ratio, 0.025 mol of NaOH will react with 0.025 moles of HCl.

Remaining moles of HCl = 0.075 - 0.025 = 0.050

Total volume of the solution = 0.250 L + 0.100 L = 0.350 L

So, the concentration of HCl in the resulting solution = \frac{0.050mol}{0.350L}

= 0.143 M

Hence, the concentration of HCl acid in the resulting solution is 0.143 M.

5 0
3 years ago
I have an important test coming up!!! i need help with thisss!!!!
Aleks [24]
I think it’s A because each unit is worth 3
7 0
2 years ago
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1.As per the Aufbau principle, which of the following orbitals have the lowest energy?
madam [21]

The correct answer attached in file, Thank you for joining brainly community.

3 0
2 years ago
Calculate the standard molar enthalpy for the complete combustion of liquid ethanol (C2H5OH) using the standard enthalpies of fo
PSYCHO15rus [73]

Answer:

Explanation:

For the reaction

C2H5OH (l) + 3 O2(g) = 2CO2(g) + 3 H2O

We can calculate the  standard molar enthalpy of combustion using the standard enthalpies of formation of the species involved in the reaction according to Hess law:

ΔHºc =  2ΔHºf CO2 (g) + 3ΔHºfH2O(l)  - ( ΔHºf C2H5OH (l) - 3ΔHºfO2 (g) )

( we were not give the water state but we know we are at standard conditions so it is in its liquid state )

The ΔHºfs can be found in appropiate reference or texts.

ΔHºc =  2ΔHºf CO2 (g)+ 3ΔHºfH2O(l)  - (  ΔHºf C2H5OH (l) -+3ΔHºfO2 (g) )

= [ 2 ( -393.52 ) + 3 ( -285.83 ) ] - [(  -276.2 + 0 ) ] kJ

ΔHºc =  -1368.33 kJ

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3 years ago
13. Which could be true about an unknown sample with a pH of 7? (2 points)
laiz [17]
The best and most correct answer among the choices provided by your question is the first choice or letter A.

A ph of 7 contains only water.

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!
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2 years ago
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