CHEMISTRY HIGH SCHOOL

Cold packs are used to treat minor injuries. Some cold packs contain NH4NO3(s) and a small packet of water at room temperature before activation. To activate this type of cold pack, the small packet must be broken to mix the water and NH4NO3(s). The temperature of this mixture decreases to approximately 2°C and remains at this temperature for 10 to 15 minutes.State the direction of heat flow that occurs when the activated cold pack is applied to the body.
Identify both types of bonds in the NH4NO3(s).

Answers

Answer 1
Answer: These types of reactions are called endothermic reactions. This is when the system absorbs the heat from the surrounding. In this case, the system is the chemical reaction and the environment is the direct vicinity of the chemical reaction. You notice that the pack becomes cold because heat from the surrounding is being absorb. 

The bonds involved in this substance includes ionic bonding and polar covalent. 

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Which of these does not describe the wright brothers first attempts at flight

Answers

Are there options for answers
As planned and went well. ( something positive most likely) but would need further info from the question to be sure

Positrons are spontaneously emitted from the nuclei of(1) potassium-37 (3) nitrogen-16
(2) radium-226 (4) thorium-232

Answers

Answer: Option (1) is the correct answer.

Explanation:

  • A positron is a small particle which contains a +1 charge and its mass is equal to the mass of an electron, that is, 9.109 * 10^(-31) kg.

A positron is represent by the symbol ^(0)_(+1)\beta.

For example, ^(37)_(19)K \rightarrow ^(37)_(18)Ar + ^(0)_(+1)\beta

  • Whereas nitrogen-16 does not decay to give a positron because nitrogen-16 is the daughter isotope formed due to decay of oxygen-16.

The decay reaction is as follows.

           ^(16)_(8)O \rightarrow ^(16)_(7)N + ^(0)_(+1)\beta

  • And, on radioactive decay of thorium-232 there will be formation of radium-228 along with emission of an alpha particle.

The reaction will be as follows.

            ^(232)_(90)Th \rightarrow ^(228)_(88)Ra + ^(4)_(2)\alpha

Therefore, we can conclude that out of the given options positrons are spontaneously emitted from the nuclei of potassium-37.
Positrons are spontaneously emitted from the nuclei of potassium -37.

Which information about a chemical reaction is provided by a potential energy diagram?

Answers

An energy profile of a reaction tells you whether it's endothermic or exothermic, the energy of the products and reactants, the activation energy needed for the forward (Ea) and reverse (Ea') reactions, the change in energy (∆E), and the energy of the activated complex.

Tin-126 has a half life of 100,000 years. How many years does it take toreduce 100 g of Tin-126 to 12.5 g?
100,000 years
200,000 years
50,000 years
300,000 years

Answers

Answer:

300,000 years

Explanation:

100g=0 years

50g=100,00 years

25g=200,00 years

12.5g=300,000 years
300’000 yes I think she is correct

Which of the following is not a colligative property of a solution?a. boiling point elevation
b. density
c. vapor pressure lowering
d. freezing point depression

Answers

The correct answer is (b.) density. Colligative properties are more concerned about the ratio between the number of particles of the solute and solvent in rather than the type of chemical or element present. Since boiling point elevation, vapor and osmotic pressure lowering and freezing point depression are considered as one of the colligative properties, it is definitely the density that does not belong to the group.

Answer:

B. Density

Explanation:

Explanation via Educere

These two compounds are in the liquid phase at 293 K a. Br₂ and Hg
b. Cl2 and F2
c. NH4^{+} and H₃O^{+}
d. Fe and Co
e. Diamond and graphite

Answers

It should be br and hg
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