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Dmitry [639]
2 years ago
13

When an athlete gets hurt they apply sometimes an instant cold pack to the injury. The instant cold pack works by mixing two che

micals that create a chemical reaction. What evidence is there that a chemical reaction is taking place in the cold pack?
Chemistry
1 answer:
NeX [460]2 years ago
3 0

Answer:

The evidence showing that there is a chemical reaction taking place is the instantaneous temperature drop once the cold pack is shaken.

Explanation:

When an athlete applies a cold pack to the injury, they shake it before, mixing the water and <em>ammonium-nitrate fertilizer</em> inside the cold pack. This mixing is an endothermic reaction, which means it absorbs heat. In turn, the temperature falls to 35 F for around 10 minutes.

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Iron (Fe) undergoes an allotropic transformation at 912°C: upon heating from a BCC (α phase) to an FCC (γ phase). Accompanying t
-Dominant- [34]

Answer:

The description including its given problem is outlined in the following section on the clarification.

Explanation:

The given values are:

RBCC = 0.12584 nm

RFCC = 0.12894 nm

The unit cell edge length (ABCC) as well as the atomic radius (RBcc) respectively connected as measures for BCC (α-phase) structure:

√3 ABCC = 4RBCC

⇒  ABCC = \frac{4RBCC}{\sqrt{3} }

⇒             = \frac{4\times 0.12584}{\sqrt{3}}

⇒             = 0.29062 \ nm

Likewise AFCC as well as RFCC are interconnected by  

√2AFCC = 4RFCC

⇒  AFCC = \frac{4RFCC}{\sqrt{2}}

⇒             = \frac{4\times 0.12894}{\sqrt{2} }

⇒             = 0.36470 \ nm

Now,

The Change in Percent Volume,

= \frac{V \ final-V \ initial}{V \ initial}\times 100 \ percent

= \frac{(VFCC)unit \ cell-(VBCC)unit \ cell}{(VBCC)unit \ cell}\times 100 \ percent

= \frac{(aFCC)^3-(aBCC)^3}{(aBCC)^3}\times 100 \ percent

= \frac{(0.36470)^3-(0.29062)^3}{(0.29062)^3}\times 100 \ percent

= 97.62 \ percent (approximately)

Note: percent = %

7 0
2 years ago
To gravimetrically analyze the silver content of a piece of jewelry made from an alloy of Ag and Cu, a student dissolves a small
Ipatiy [6.2K]

Answer:

Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions.

Explanation:

The student have in solution Ag⁺ and Cu²⁺ ions but he just want to analyze the silver, that means he need to separate ions.

Centrifuging the solution to isolate the heavier ions <em>FALSE </em>Centrifugation allows the separation of a suspension but Ag⁺ and Cu²⁺ are both soluble in water.

Adding enough base solution to bring the pH up to 7.0 <em>FALSE </em>At pH = 7,0 these ions are soluble in water and its separation will not be possible.

Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions <em>TRUE </em>For example, the addition of Cl⁻ will precipitate the Ag⁺ as AgCl(s) allowing its separation.

Evaporating the solution to recover the dissolved nitrates. <em>FALSE</em> . Thus, you will obtain the nitrates of these ions but will be mixed doing impossible its separation.

I hope it helps!

8 0
2 years ago
The acid HOCl (hypochlorous acid) is produced by bubbling chlorine gas through a suspension of solid mercury(II) oxide particles
skelet666 [1.2K]

Answer:

k = \frac{[HOCl]^2}{[Cl]^2}

Explanation:

The equilibrium-constant expression is defined as the ratio of the concentration of products over concentration of reactants. Each concentration is raised to the power of their coefficient.

Also, pure solid and liquids are not included in the equilibrium-constant expression because they don't affect the concentration of chemicals in the equilibrium

The global reaction is:

2 HgO (s) + H₂O (l) +2 Cl₂ (g) ⇌ 2 HOCl (aq) + HgO⋅HgCl₂ (s)

Thus, equilibrium-constant expression is:

<em>k = \frac{[HOCl]^2}{[Cl]^2}</em>

You don't include HgO nor HgO⋅HgCl₂ because are pure solids nor water because is pure liquid.

I hope it helps!

4 0
2 years ago
Give the structures of the substitution products expected when 1-bromohexane reacts with: part a naoch2ch3
Yuri [45]

Actually since Bromine is located at the 1 Carbon, so we can say that this is a primary alkyl halide and which undergoes SN2 or E2 reactions. This reaction is a bimolecular, single step process because it is a primary.

<span>The substitution product formed will be 1-ethoxybutane (main product) and sodium bromide (side product).</span>

5 0
2 years ago
(4) strontium (sr) has an fcc crystal structure, an atomic radius of 0.215 nm and an atomic weight of 87.62 g/mol. calculate the
OleMash [197]
<span>2.59 g/cm^3 For a face centered cubic crystal, there is 1 atom at each corner that's shared between 8 unit cells. And since there's 8 corners, that gives 8*1/8 = 1 atom per unit cell. Additionally, there are 6 faces, each with 1 atom, that's shared between 2 cells. So 6*1/2 = 3. So each unit cell has a mass of 1 + 3 = 4 atoms. The size of the unit cell will be equal to either the diameter of one atom along the edge, or the diameter of 2 atoms as the diagonal across one face of the cube, whichever results in the larger unit cell. Taking that into consideration, I will use the value of 2 for the diagonal of a face of the unit cell, resulting in the length of an edge of the unit cell being sqrt(2^2/2) = sqrt(2) = 1.414213562 times the atomic diameter. So 1.414213562 * 2 * 0.215 nm = 0.608 nm So the volume of a single unit cell is (0.608 nm)^3 Avogadro's number of atoms will require 6.0221409x10^23 / 4 = 1.50554x10^23 unit cells and will have a mass of 87.62 grams. The volume will be 1.50554x10^23 * (0.608x10^-7 cm)^3 = 1.50554x10^23 * 0.224755712x10^-22 cm^3 = 33.83776414 cm^3 So the density is approximately 87.62 g/33.83776414 cm^3 = 2.589414585 g/cm^3, when rounded to 3 significant figures is 2.59 g/cm^3.</span>
7 0
2 years ago
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