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3 years ago

What are some properties of matter that can be identified without testing or measuring

Chemistry

1 answer:

kiruha [24]3 years ago

8 0

Physical change - No change of matter in this phase
chemical change - All types of phase change occur here

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Find the ph of a 0.250 m solution of nac2h3o2. (the ka value of hc2h3o2 is 1.80×10−5). express your answer numerically to four s

Slav-nsk [51]

Answer is: pH value of solution of NaC₂H₃O₂ is 9.07.
Chemical reaction: C₂H₃O₂⁻ + H₂O ⇄ HC₂H₃O₂ + OH⁻.
Ka(HC₂H₃O₂) = 1,8·10⁻⁵.
Ka · Kb = Kw.
1,8·10⁻⁵ mol/dm³ · Kb = 1·10⁻¹⁴ mol²/dm⁶; the ionic product of water at 25°C.
Kb(C₂H₃O₂⁻) = 1·10⁻¹⁴ mol²/dm⁶ ÷ 1,8·10⁻⁵ mol/dm³.
Kb(C₂H₃O₂⁻) = 5,56·10⁻¹⁰ mol/dm³.
c(C₂H₃O₂⁻) = 0,25 M.
[OH⁻] = [HC₂H₃O₂] = x.
[C₂H₃O₂⁻] = 0,25 M - x.
Kb = [OH⁻] · [HC₂H₃O₂] / [C₂H₃O₂⁻].
5,56·10⁻¹⁰ = x² / (0,25 M -x).
Solve quadratic equation: x = [OH⁻] = 0,0000118 M.
pOH = -log[OH⁻] = -log(0,0000118M) = 4,93.
pH + pOH = 14.
pH = 14 - 4,93 = 9,07.

6 0

3 years ago

What elements are being reduced and oxidized in this chemical formula?

dangina [55]

Answer: The element Na (Sodium) is getting oxidized and Hydrogen is getting reduced.

Explanation:

Oxidation reactions are the reactions in which addition of oxygen takes place.

Reduction reactions are the reactions in which loss of oxygen takes place.

For a given reaction:

$2Na(s)+2H_2O(l)\rightarrow H_2(g)+2NaOH(aq.)$

Sodium is getting oxidized because there is an addition of reaction with that element.

Hydrogen is getting reduced because there is a removal of oxygen with that element.

3 0

3 years ago

How many moles are there in 3.612 x 1024 formula units of Na2SO4?

vitfil [10]

Answer:

<h3>Theanswer is 6 moles</h3>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

$n = \frac{N}{L} \\$

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

$n = \frac{3.612 \times {10}^{24} }{6.02 \times {10}^{23} } \\$

We have the final answer as

<h3>6 moles</h3>

Hope this helps you

5 0

3 years ago

What is heating and cooling

melisa1 [442]

make or become hot or warm is heating.

cooling is to become colder or cool down from a higher temp.

6 0

4 years ago

The line graph shows the heights of plants grown in fertilized and unfertilized soil. Based on this information, what will most

AfilCa [17]

Answer:

g) Neither plant should increase by 1 cm in height.

Explanation:

See the graph for this question on the figure attached.

The growing of the plant A is represented by the line that goes above the other. At start, that line has a slope that rises about 0.75 cm ( height increase) in 1 day. From the day 2 and forward the slope of the line decreases. The line reaches its highest point about at day 4 and seems to start decreasing. Thus, you should predict that on the day six it most likely does not increase in height.

The growing of the plant B is represented by the line drawn below the other. As for the plant B, the growing decreases with the number of days. Between the days 4 and 5 the line is almost flat, which means that most likely this plant will not grow on the day six or grow less than 0.5 cm.

Thus, for both plants you can say that on day six, most likley, neither should increase by 1 cm in height (option g).

4 0

3 years ago