Answer:- 
molecules.
Solution:- The grams of tetrabromomethane are given and it asks to calculate the number of molecules.
It is a two step unit conversion problem. In the first step, grams are converted to moles on dividing the grams by molar mass.
In second step, the moles are converted to molecules on multiplying by Avogadro number.
Molar mass of 
= 12+4(79.9) = 331.6 g per mol
let's make the set up using dimensional analysis:
= molecules
So, there will be molecules in 250 grams of .
Answer:
Conversion of kinetic energy to potential energy (chemo mechanical energy)
In the state of rest, the rubber is a tangled mass of long chained cross-linked polymer that due to their disorderliness are in a state of increased entropy. By pulling on the polymer, the applied kinetic energy stretches the polymer into straight chains, giving them order and reducing their entropy. The stretched rubber then has energy stored in the form of chemo mechanical energy which is a form of potential energy
Conversion of the stored potential energy in the stretched to kinetic energy
By remaining in a stretched condition, the rubber is in a state of high potential energy, when the force holding the rubber in place is removed, due to the laws of thermodynamics, the polymers in the rubber curls back to their state of "random" tangled mass releasing the stored potential energy in the process and doing work such as moving items placed in the rubber's path of motion such as an object that has weight, w then takes up the kinetic energy 1/2×m×v² which can can result in the flight of the object.
Explanation:
Answer:
Exothermic reaction: In exothermic reaction, energy is transferred to the surroundings, and the surrounding temperature increases, this is known as exothermic reaction. In other words energy exits in exothermic reaction. Some example of exothermic reactions are:
1) Neutralisation reaction.
2) Combustion reaction.
3) Some oxidation reaction.
Endothermic reaction: In endothermic reaction, energy is taken in from the surrounding, and the surrounding temperature decreases, this is known as endothermic reaction. In other words energy enters in endothermic reaction. Some example of exothermic reactions are:
1) Thermal decomposition.
2) Reaction between citric acid and sodium hydrogen carbonate.
Answer:
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Explanation:
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<u>1. Dissociation equation</u>
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Assuming 100% dissociation, the equation is:
- Ba(C₂H₃O₂)₂ → Ba²⁺ + 2C₂H₃O₂⁻
↑
acetate ions
<u>2. Molarity</u>
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Calculate the molarity, M, of the solution:
- n = mass in grams / molar mass
- n = 69.g / 255.415g/mol = 0.27015 mol
- M = 0.27015mol / 0.970liter = 0.27850 mol/liter ≈ 0.28M
<u>3. Acetate ions</u>
From the chemical equation, 1 mol of dissolved Ba(C₂H₃O₂)₂ produces 2 acetate ions in solution.
Thus, 0.28 mol/liter × 2 = 0.56 mol/liter = 0.56M ← answer
The molar masses of H2S and NH3 are 34 and 17 g/mol, respectively. The equation that would best represent the given is,
Rate A/Rate B = √(molar mass B/molar mass A)
Substituting,
x/77 = √(17 /34 )
x = 54.4
Thus, it will take 54.4 seconds for NH3 to travel through the container.
