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irina1246 [14]
3 years ago
14

H2O2, hydrogen peroxide, naturally breaks down into H2O and O2 over time. MnO2, manganese dioxide, can be used to lower the ener

gy of activation needed for this reaction to take place and, thus, increase the rate of reaction. What type of substance is MnO2 ?
a. a reactant

b. an inhibitor

c. an enhancer

d. a catalyst
Chemistry
1 answer:
Lostsunrise [7]3 years ago
5 0

The answer is A because it is a reactant

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What salt is produced in each of the following neutralization reactions?
Pavlova-9 [17]

1. Salt is KNO₃<span>

<span>This is a </span>strong acid - strong base<span> <span>reaction. </span></span>HNO</span>₃ is the strong acid<span> <span>and </span></span>KOH is the strong base<span>. </span><span>

H</span>⁺<span> in the HNO₃<span> and </span></span>OH⁻<span> <span>of the KOH pair up and make </span></span>H₂O(l)<span>. </span><span>

NO</span>₃⁻<span> <span>and </span></span>K⁺<span> <span>pair up to make </span></span>KNO₃ salt<span>. </span><span>

<span>When writing chemical formulas </span>positive ion comes first<span> <span>and second is negative ion. The charges should be switched. Since </span></span>positive ion has +1 and negative ion has -1<span> <span>after the switching off charges </span>the </span>product should be KNO</span>₃.<span>

Balance equation is </span><span>
HNO</span>₃<span>(aq) + KOH(aq) → H</span>₂O(l) + KNO<span>₃(aq)</span><span>
<span>
2. Salt is Ca(NO</span></span>₃)₂<span>

</span>This is a strong acid - strong base<span> reaction. </span>HNO₃ is the strong acid<span> and </span>Ca(OH)₂ is the strong base<span>. </span><span>
<span>
H</span></span>⁺<span> in the HNO₃ and </span>OH⁻<span> of the Ca(OH)₂ pair up and make </span>H₂O(l)<span>. </span><span>

Ca²⁺ and </span>NO₃⁻<span>  pair up to make </span>Ca(NO₃)₂ salt<span>. </span><span>
<span>
</span><span>Positive ion is </span>Ca²⁺<span> which has </span></span>+2 charge<span> and negative ion is</span> NO₃⁻<span> <span>which has </span></span>-1 charge<span>. From switching the charges </span>Ca²⁺ gets 1<span> <span>while </span></span>NO₃⁻ gets 2.<span> Hence, the salt should be </span>Ca(NO₃)₂.<span>

Balanced equation is 
</span>2HNO₃<span>(aq) + Ca(OH)</span>₂<span>(aq) → 2H</span>₂O(l) + Ca(NO<span>₃)₂(aq)</span><span>
<span>
3. Salt is CaCl</span></span>₂<span>

This is a strong acid - strong base<span> reaction. </span>HCl is the strong acid<span> and </span>Ca(OH)</span>₂ is the strong base<span>. </span><span>
<span>
H</span></span>⁺<span> in the HCl and </span>OH⁻<span> of the Ca(OH)₂ pair up and make </span>H₂O(l)<span>. </span><span>

Ca²⁺ and </span>Cl⁻<span> pair up to make </span>CaCl₂ salt<span>. </span><span>
<span>
</span><span>Positive ion is </span>Ca²⁺ which has </span>+2 charge<span> and negative ion is</span> Cl⁻<span> which has </span>-1 charge<span>. By switching the charges </span>Ca²⁺ gets 1<span> while </span>NO₃⁻ gets 2.<span> Hence, the salt should be </span>CaCl₂.<span>

Balance equation is 
</span><span>2HCl(aq) + Ca(OH)</span>₂<span>(aq) → 2H</span>₂O(l) + CaCl₂<span>(aq)

4. Salt is KCl<span>

</span>This is a strong acid - strong base<span> reaction. </span>HCl is the strong acid<span> and </span>KOH is the strong base<span>. </span>
<span>
H</span></span>⁺<span> in the HCl and </span>OH⁻<span> of the KOH pair up and make </span>H₂O(l)<span>. </span><span>

K</span><span>⁺ and </span>Cl⁻<span> pair up to make </span>KCl salt<span>. </span><span>
<span>
</span><span>Positive ion is K</span></span><span>⁺ which has </span>+1 charge<span> and negative ion is</span> Cl⁻<span> which has </span>-1 charge<span>. By switching the charges </span>K⁺ gets 1<span> and </span>Cl⁻ also gets 1.<span> Hence, the salt should be </span>KCl.<span>

Balance equation is 
</span><span>HCl(aq) + KOH(aq) → H</span>₂<span>O(l) + KCl(aq)</span>

5 0
3 years ago
Read 2 more answers
What led Marie Curie to draw the following conclusions? (b) A highly radioactive element, aside from uranium, occurs in pitchble
AVprozaik [17]

Making repeated separations of the various substances in the pitchblende, Marie and Pierre used the Curie electrometer to identify the most radioactive fractions. They thus discovered that two fractions, one containing mostly bismuth and the other containing mostly barium, were strongly radioactive.

<h3>What was surprising about pitchblende?</h3>

Since it was no longer appropriate to call them “uranic rays,” Marie proposed a new name: “radioactivity.”

Even more surprising, Marie next found that a uranium ore called pitchblende contained two powerfully radioactive new elements: polonium, which she named for her native Poland, and radium.

<h3>Why is radium more radioactive than uranium?</h3>

It is 2.7 million times more radioactive than the same molar amount of natural uranium (mostly uranium-238), due to its proportionally shorter half-life.

Learn more about highly radioactive elements here:

<h3>brainly.com/question/10257016</h3><h3 /><h3>#SPJ4</h3>

6 0
2 years ago
Which pair of elements are in the same period?Hg &amp; PbLi &amp; NaB &amp; ClO &amp; As
Alexeev081 [22]

Answer:

Hg Pb are in one, Li and B and O are in one, and NaCl are in one, As is alone

Explanation:

Periods are horizontal

Hope this helps!

4 0
2 years ago
What is true of saturated fatty acids?
Natali5045456 [20]

Answer:

The second answer, because when something saturated, it has the maximum possible number of hydrogen atoms.

7 0
3 years ago
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The half life of 226/88 Ra is 1620 years. How much of a 12 g sample of 226/88 Ra will be left after 8 half lives?
Aloiza [94]

Answer:

0.0468 g.

Explanation:

  • The decay of radioactive elements obeys first-order kinetics.
  • For a first-order reaction: k = ln2/(t1/2) = 0.693/(t1/2).

Where, k is the rate constant of the reaction.

t1/2 is the half-life time of the reaction (t1/2 = 1620 years).

∴ k = ln2/(t1/2) = 0.693/(1620 years) = 4.28 x 10⁻⁴ year⁻¹.

  • For first-order reaction: <em>kt = lna/(a-x).</em>

where, k is the rate constant of the reaction (k = 4.28 x 10⁻⁴ year⁻¹).

t is the time of the reaction (t = t1/2 x 8 = 1620 years x 8 = 12960 year).

a is the initial concentration (a = 12.0 g).

(a-x) is the remaining concentration.

∴ kt = lna/(a-x)

(4.28 x 10⁻⁴ year⁻¹)(12960 year) = ln(12)/(a-x).

5.54688 = ln(12)/(a-x).

Taking e for the both sides:

256.34 = (12)/(a-x).

<em>∴ (a-x) = 12/256.34 = 0.0468 g.</em>

8 0
3 years ago
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