Answer:
Physical Change
Explanation:
A solid being crushed into a powder is a physical change because a chemical change is when substances combine to create new substances.
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8) Structures that regulate which molecules,
nutrients, and substances enter the cell are
A) Genes
B) Endoplasmic Reticulum
C) Cell Membranes
D) Centrioles
When 0.717 g of sodium metal is added to an excess of hydrochloric acid, 7450 J of heat are produced. What is the enthalpy of the reaction as written?
2Na(s)+2HCl(aq)⟶2NaCl(aq)+H2(g)
Answer:
The enthalpy change of the reaction is 4.78 × 10⁴ J.
Explanation:
We are given that 0.717 g of sodium metal reacts with hydrochloric acid to produce 7450 J of heat.
Converting grams of sodium to moles:
[tex]\displaystyle 0.717 \text{ g Na} \cdot \frac{1 \text{ mol Na}}{22.99 \text{ g Na}} = 0.0312 \text{ mol Na}[/tex]
And dividing the amount of heat produced by the moles of sodium reacted yields:
[tex]\displaystyle \Delta H = \frac{7450 \text{ J}}{0.312 \text{ mol Na}} = 2.39 \times 10^4 \text{ J/mol Na}[/tex]
Because the given reaction has two moles of sodium metal, we can multiply the above value by two to acquire the enthalpy change of the given reaction:
[tex]\displaystyle \Delta H = 2\text{ mol Na}\left(2.39 \times 10^4 \text{ J/mol Na}}\right) = 4.78 \times 10^4 \text{ J}[/tex]
In conclusion, the enthalpy change of the reaction is 4.78 × 10⁴ J.
To what energy level do the electrons drop when visible light is produced?
Answer: The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level. When the electron changes from n=3 or above to n=2, the photons emitted fall in the Visible Light region of the spectra
Most chloride salts are soluble. Which of the following is an exception to this generalization?
A. NH4Cl
B. AlCl3
C. ZnCl2
D. CuCl2
E. PbCl2
The exception to the rule concerning the solubility of chlorides in water is PbCl2.
The solubility rules give us an idea of which substances are soluble in water and what substances are not soluble in water. According to the solubility rules, chlorides are soluble in water.
However, chlorides of lead are not soluble in water hence, the exception to the rule is PbCl2.
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From the options given, the chloride salt that is not soluble is PbCl₂.
Solubility simply means the ability of liquid, solid, or gaseous chemical substance to be bake to dissolve in solvent and then form a solution.
It should be noted that most chloride salts are soluble. Examples include NH₄Cl, AlCl₃, ZnCl₂, CuCl₂, etc. However, the chloride of lead aren't soluble in water. Therefore, PbCl₂ isn't soluble in water.
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Use the image to answer the question.
An illustration shows the process that takes place in a cold pack. The warm cold pack has ammonium nitrate on one side and water on the other. The water is kept separate in a thin plastic bag. The pack is squeezed and the inner bag bursts. The mixture cools as ammonium nitrate dissolves.
Which kind of reaction is shown in this image?
(1 point)
It is an endothermic reaction because the system takes energy from the surroundings.
It is an exothermic reaction because the surroundings take energy from the system.
It is an endothermic reaction because the surroundings take energy from the system.
It is an exothermic reaction because the system takes energy from the surroundings.
Answer:
it is an endothermic reaction because the system takes energy from the surrounding.
Answer:
It is an endothermic reaction because the system takes energy from the surroundings.
Explanation:
I did the test.
what does feldspar mean?
Answer:
an abundant rock-forming mineral typically occurring as colorless or pale-colored crystals and consisting of aluminosilicates of potassium, sodium, and calcium.
Explanation:
Answer:
Feldspars are a group of rock-forming aluminium tectosilicate minerals, containing sodium, calcium, potassium or berium
How does the release of energy and nutrients from digestion help the rest of the body's system?
Answer:
[tex]^{}[/tex] in a file
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bit.[tex]^{}[/tex]
Explanation: