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erastova [34]
3 years ago
8

Why is heat needed to get a reaction to occur

Chemistry
2 answers:
olga2289 [7]3 years ago
8 0

Answer:

Endothermic and Exothermic Reactions

Many familiar chemical reactions, such as the burning of coal, rusting and exploding gunpowder, give off heat; chemists call these reactions exothermic. Because reactions liberate heat, they increase the ambient temperature.

Ahat [919]3 years ago
4 0

Answer:As temperature increases, reactions take place. Generally, higher temperatures mean faster reaction rates; as molecules move about more quickly, reactant molecules are more likely to interact, forming products.

Explanation:

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A minimumenergy of 7.21x10-19 J is required to produce the photoelectric effect in chromium metal.
forsale [732]

Answer:

<em>2.085 x 10^-20 J</em>

<em></em>

Explanation:

minimum energy required to produce photoelectric effect in chromium is given as hf =  7.21 x 10^-19 J

The work function of chromium Ф = 4.37 eV = 7.00151 x 10^-19 J

The minimum energy required to eject an electron from from a chromium metal E = ?

From E = hf - Ф

substituting values, we have

E = (7.21 x 10^-19) - (7.00151 x 10^-19)

E = <em>2.085 x 10^-20 J</em>

7 0
3 years ago
1. If you have a sample of gas at a pressure of 16 atm, what will the pressure be if the volume is halved?
vagabundo [1.1K]

Answer:

1. The pressure will be 32 atm, twice the initial pressure.

2. The pressure will be 1.83 atm, one third of the initial pressure.

Explanation:

Boyle's law is one of the gas laws that relates the volume and pressure of a certain quantity of gas kept at a constant temperature.

This law says that "The volume occupied by a given gaseous mass at constant temperature is inversely proportional to pressure." This means that if the pressure increases, the volume decreases, while if the pressure decreases, the volume increases.

Boyle's law is expressed mathematically as:

Pressure * Volume = constant

or P * V = k

Ahora es posible suponer que tienes un cierto volumen de gas V1 que se encuentra a una presión P1 al comienzo del experimento. Si varias el volumen de gas hasta un nuevo valor V2, entonces la presión cambiará a P2, y se cumplirá:

P1*V1=P2*V2

1. In this case:

  • P1= 16 atm
  • V1
  • P2= ?
  • V2= V1÷2= \frac{V1}{2} because the volume is halved.

So:

16 atm*V1= P2* \frac{V1}{2}

Solving:

\frac{16 atm*V1*2}{V1}=P2

16 atm*2= P2

32 atm= P2

<u><em>The pressure will be 32 atm, twice the initial pressure.</em></u>

2. Now

  • P1= 5.5 atm
  • V1
  • P2= ?
  • V2= V1*3 because the volume is tripled.

So:

5.5 atm*V1= P2* V1*3

Solving:

\frac{5.5 atm*V1}{3*V1}=P2

\frac{5.5 atm}{3}= P2

1.83 atm= P2

<u><em>The pressure will be 1.83 atm, one third of the initial pressure.</em></u>

7 0
3 years ago
a student performed an experiment, using a cocktail peanut, before it was burned the peanut half weighed .353 g. After burning t
tekilochka [14]
Not sure but it should be on google
5 0
3 years ago
It’s science, the subject is light and color
vladimir1956 [14]

Answer:

22)convex

23)sun (sunlight reflect of the off the surface of the moon

24)because of the way the atmosphere interacts with sunlight

25) transparent : glass,contact lenses,water,air

translucent: wax paper, oil paper, thin sheets

opaque : plastic, wood, leather

26)when light react with opaque: none of it passes though

when it reacts with transparent : it passes through

when it react with translucent : only some of it passes through, the light does not pass directly through the material

Explanation:

24 blue light is scattered in all directions by the tiny molecules of air in earth's atmosphere

8 0
3 years ago
Why do you think different liquids have different freezing points
Ganezh [65]
I think that different liquids have different freezing points because every liquid consists of different atoms and different things that make up the atom causing them to have different freezing points.
5 0
3 years ago
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