Which of the following would heat up the quickest?

g A 500. mL solution contains 0.665 M NaC2H3O2 and 0.475 M HC2H3O2. What mass of HCl in grams needs to be added for the solution

77julia77 [94]

Answer:

7.38g HCl

Explanation:

Using H-H equation for acetic buffer:

pH = pKa + log [NaC2H3O2] / [HC2H3O2]

Where pKa is -log Ka = 4.74 and [] could be taken as moles of each compound.

The initial moles of each specie is:

[NaC2H3O2]:

0.500L * (0.665mol/L) = 0.3325moles

[HC2H3O2]:

0.500L * (0.475mol/L) = 0.2375 moles

That means total moles are:

[NaC2H3O2] + [HC2H3O2] = 0.57 moles (1)

And solving H-H equation for a pH of 4.21:

4.21 = 4.74 + log [NaC2H3O2] / [HC2H3O2]

0.29512 = [NaC2H3O2] / [HC2H3O2] (2)

Replacing (1) in (2):

0.29512 = 0.57mol - [HC2H3O2] / [HC2H3O2]

0.29512 [HC2H3O2] = 0.57mol - [HC2H3O2]

1.29512 [HC2H3O2] = 0.57mol

[HC2H3O2] = 0.44 moles

The HCl reacts with NaC2H3O2 producing HC2H3O2, that means you need to add:

0.44 moles - 0.2375 moles =

0.2025 moles of HCl

Using molar mass of HCl (36.45g/mol), to convert these moles to grams:

0.2025 moles * (36.45g/mol) =

8 0

3 years ago

What is true about all plutons? They form near Earth’s surface. They form below Earth’s surface. They cut across other rock laye

pishuonlain [190]

Answer: The correct answer is that they are formed below Earth's surface.

Explanation:

Plutons are defined as the intrusive igneous rocks named as plutonic rocks which are formed when the magma gets cools down slowly and solidifies below the Earth's surface.

It is different from volcanic rocks which are formed when lava gets cools down and solidifies on the Earth's surface.

Hence, the correct answer is that they are formed below Earth's surface.

7 0

3 years ago

Read 2 more answers

Which of the following statements is true for radioactive reactions:

sasho [114]

Answer:

d) Nucleus of the element does not change during the react

hope it helps (^^)

# Cary on learning

8 0

2 years ago

Read 2 more answers

What is spectrophotometry? How can this be useful in identifying drugs?

liq [111]

Answer:

What is spectrophotometry? It is an analytic method that it use substances light absorbance property

How can this be useful in identifying drugs? It possible compare spectra and identify problem substance

Explanation:

The way substances absorb light is unique and because of that it is possible to use spectrophotometry for substances identifying. the model spectra are measured in ideal conditions, so, it is difficult ensure the same conditions and to achieve identical spectra.

I hope I have been helpful

7 0

3 years ago

Explain the difference between ecosystem, community, and population.

Studentka2010 [4]

Out of the three you gave ecosystem is what I would call the most broad. An ecosystem includes living AND non-living things in an area

Community is all the LIVING things in an area (plants are included and I think bacteria is too, but I'm not sure)

Population is pretty narrow it just looks at specific species in one area. Population of mosquitoes doesn't include butterflies, if only looks at mosquitoes

Hope this helped!

4 0

3 years ago