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Lemur [1.5K]
3 years ago
8

Changes in thermal energy provide evidence that a chemical reaction

Chemistry
1 answer:
nadya68 [22]3 years ago
7 0

Answer:

Exothermic reaction

Explanation:

Exothermic reaction is a reaction in which energy is evolved from the reaction to the surroundings

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A student claims that if she wanted to make a solution quickly, she should use small pellets instead of powder along with heatin
vova2212 [387]

Answer: Yes we agree with the student's claim.

Explanation:

When the molecules are present in smaller size, more reactants can react as decreasing the size increases the surface area of the reactants which will enhance the contact of molecules.Hence, more products will form leading to increased rate of reaction.

On increasing the temperature will make more reactant molecules will have sufficient energies to cross the energy barrier and thus the number of effective collisions increases, thus leading to more products and increased rate of reaction.

When the solution is stirred , the molecule's kinetic energy and thus the rate of reaction increases.

Thus smaller size, stirring and increase of temperature will make the solution quickly.

7 0
3 years ago
Which is true about the total mechanical energy in a closed system?
ryzh [129]
It’s between C and B
3 0
3 years ago
Read 2 more answers
You have a 25.2 L sample of gas at 1.25 atm and 25.0 degrees Celsius. How many moles are present in this gas. For your answer, p
Elenna [48]

Answer:

  • <u>1.29 mol</u>

Explanation:

This is a direct application of the equation for ideal gases.

  • PV=nRT

Where:

  • P = pressure = 1.25 atm
  • V = volume = 25.2 liter
  • R = Universal constant of gases = 0.08206 atm-liter/K-mol
  • T = absolute temperature = 25.0ºC = 25 + 273.15 K = 298.15 K
  • n = number of moles

Solving for n:

  • n=\frac{PV}{RT}

Substituting:

n=\frac{1.25atm\times 25.2liter}{0.08206atm-liter/K-mol\times298.15K }\\\\n=1.29mol

8 0
3 years ago
What is the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.0×1015Hz?
Anvisha [2.4K]
In order to emit electrons, the cesium will have to absorb photons. Each photon will knock out one electron by transferring its energy to the electron. Therefore, by the principle of energy conservation, the energy of the removed electron will be equal to the energy of the incident photon. That energy is calculated using Planck's equation:

E = hf

E = 6.63 x 10⁻³⁴ * 1 x 10¹⁵
E =  6.63 x 10⁻¹⁹ Joules

The electron will have 6.63 x 10⁻¹⁹ Joules of kinetic energy
3 0
3 years ago
1 mole = 1000 millimoles (mmol); 1millimole = 1000 micromoles (µmol). if a solution contains 38231 µmol, what is that amount in
Mrrafil [7]
1 mmol --------------------- 1000 <span>µmol
( mmol ) -------------------- </span> 38231 µmol

mmol =  38231*1 / 1000

mmol = 38231/ 1000

=>  38.231 mmol
3 0
3 years ago
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