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soldi70 [24.7K]
3 years ago
15

Explain how temperature can affect the speed of reaction. Give an example.

Chemistry
1 answer:
aleksley [76]3 years ago
3 0

Answer:

Chemical reactions proceed at different rates. The factors that affect reaction rates are:

surface area of a solid reactant

concentration or pressure of a reactant

temperature

nature of the reactants

presence/absence of a catalyst.

A change in one or more of these factors may alter the rate of a reaction. In this lesson, you will define these factors, and describe and predict their effects on reaction rates.

Surface Area

Surface area is the exposed matter of a solid substance.

Imagine that you are holding a perfect cube of magnesium. The surface area is the sum of the area of all six sides of the cube. The surface area of the cube can be increased by dividing the cube into smaller cubes. Surface area is maximized when a single large cube is crushed to fine powder.

The rate of reaction of a solid substance is related to its surface area. In a reaction between a solid and an aqueous/liquid/gas species, increasing the surface area of the solid-phase reactant increases the number of collisions per second and therefore increases the reaction rate.

In a reaction between magnesium metal and hydrochloric acid, magnesium atoms must collide with the hydrogen ions. When the magnesium atoms form one big lump...

The concentration of a gas is a function of the pressure on the gas. Increasing the pressure of a gas is exactly the same as increasing its concentration. If you have a certain number of gas molecules, you can increase the pressure by forcing them into a smaller volume.

Under higher pressure or at a higher concentration, gas molecules collide more frequently and react at a faster rate. Conversely, increasing the volume of a gas decreases pressure which in turn decreases the collision frequency and thus reduces the reaction rate.

It is important to note however that there are reactions involving gases in which a pressure change does not affect the reaction rate. For this reason, the rates of reactions involving gases have to be determined by experiment.

Also note that solids and liquids are not affected by pressure changes.

Need a good analogy for the effect of concentration on the rate of a chemical reaction?

Temperature

With the exception of some precipitation reactions involving ionic compounds in solution, just about all chemical reactions take place at a faster rate at higher temperatures. The question is why?

Temperature (in Kelvin degrees) is proportional to the kinetic energy of the particles in a substance. For example, if the Kelvin temperature of a substance is doubled, then the average kinetic energy of the particles in that substance is doubled.

 

At higher temperatures, particles collide more frequently and with greater intensity.

 

Here's an analogy.

Imagine that you are baby-sitting a bunch of 6 year olds. You put them in a yard and you let them run around. Every now and then a couple of kids will run into each other. Now imagine that you decide to feed them some sugar. What happens? They run around faster and of course there are many more collisions. Not only that, the collisions are likely to be a lot harder/more intense.

Now, let's look at the effect graphically. Recall that in any sample of matter (the example we used previously was a gas), individual particles have different kinetic energies. Some are moving fast some are moving slowly, and most are moving at some intermediate speed.

Increasing the temperature by say 10°C causes some of the intermediate speed molecules to move faster. The result is more molecules with sufficient kinetic energy to form an activated complex upon collision!

Now consider the relationship between threshold kinetic energy and activation energy. Threshold kinetic energy is the minimum amount of energy required for colliding particles to react - it is the equivalent of activation energy or the minimum potential energy gain required to form an activated complex.

As you can see on the graph, a small increase in temperature can double the number of molecules with the threshold kinetic energy.

Thus there are two effects of increasing temperature: greater collision intensity and more frequent collisions.

A general rule is that a 10°C temperature increase can double a reaction rate. It turns out that the increase in the reaction rate is mainly a function of the more intense collisions. Increased collision frequency is not as significant a factor.

Explanation:

You might be interested in
What volume of gold would be equal in mass to a piece of copper with a volume of 141 ml? the density of gold is 19.3 g/ml; the d
sergejj [24]
We are tasked to solve for the volume of Gold given that the mass of Gold is equivalent to that of a copper.

Details:

Density of Copper= 8.96 g/ml
Volume of Copper=141 ml
mass of Gold = mass of Copper
Density of Gold=19.3 g/ml

In order to solve for the mass of copper, we need to use the density formula
Density= mass/volume

Since we are to solve for the mass of copper
mass of copper= Density of Copper * Volume of Copper
mass of copper= 8.96 g/ml* 141 ml= 1263.36 g
Thus,
mass of gold=mass of copper=1263.36 g
Hence,
Using still the density formula to solve for the volume of gold,
Volume of gold=mass of gold/ Density of gold
Volume of gold=1263.36 g/ 19.3 g/ml = 65.46 mL

Therefore, the volume of the gold must be 65.46 mL in order to have the same mass of a copper
8 0
3 years ago
Nts
a_sh-v [17]

The reaction is a synthesis reaction.

<h3>What are synthesis reactions?</h3>

Synthesis reactions are one of the numerous reactions in chemistry. These kinds of reactions involve the combination of two atoms of different elements resulting in the formation of new compounds.

Synthesis reactions are sometimes referred to as combination reactions, simply because they have to do with the combination of two or more atoms of different elements into a single compound.

The different elements that combine are referred to as the reactants while the result of the combination is known as the product.

For example: A + B --> AB

In the illustrated reaction, N2 combined with H2 to form NH3. N2 and H2 gases are the reactants while NH3 is the only product formed from the two reactants.

This is a good example of a synthesis/combination reaction.  

More on synthesis reactions can be found here: brainly.com/question/24936069

#SPJ1

6 0
1 year ago
A 2.00 kg piece of lead at 40.0°C is placed in a very large quantity of water at 10.0°C,and thermal equilibrium is eventually re
sveticcg [70]

Answer:

Δ S = 26.2 J/K

Explanation:

The change in entropy can be calculated from the formula  -

Δ S = m Cp ln ( T₂ / T₁ )

Where ,

Δ S = change in entropy

m = mass  = 2.00 kg

Cp =specific heat of lead is 130 J / (kg ∙ K) .

T₂ = final temperature  10.0°C + 273 = 283 K

T₁ = initial temperature ,  40.0°C + 273 = 313 K

Applying the above formula ,

The change in entropy is calculated as ,

ΔS = m Cp ln ( T₂ / T₁ )  = (2.00 )( 130 ) ln( 283 K / 313 K )

ΔS = 26.2 J/K

6 0
3 years ago
Predict the product of this chemical equation. please explain how u did it. Do not balance after finding answer.
Oksanka [162]

Answer:

The products are CO₂ and H₂O.

The ballanced equation is this:

2C₄H₆ + 11O₂  →   8CO₂  +   6H₂O

Explanation:

In any chemical reaction, where you see that you have a compound reacting only with oxygen (O₂), you are in front of combustion.

Products in combustion are always water vapor and carbon dioxide.

Take a look to the methane combustion.

CH₄  +  2O₂  →  CO₂  +  2H₂O

1 mol of methane reacts with 2 moles of oxygen to form 1 mol of CO₂ and 2 moles of water.

This is the combustion for an alkene where 2 moles of the alkene reacts with 11 moles of oxygen to make water and CO₂ like this:

2C₄H₆ + 11O₂  →   8CO₂  +   6H₂O

8 0
2 years ago
Cu + 2 AgNO3 + Cu(NO3)2 + 2Ag
Allushta [10]

Answer:

7.28 moles Ag°

Explanation:

              Cu°          +    2 AgNO₃  => Cu(NO₃)₂ + 2Ag°

Given 7.28 moles     7.28 moles

To determine limiting reactant, divide the mole values by the respective coefficient of balanced equation. The resulting smallest value is the limiting reactant. Note: this is a short cut method for determining limiting reactant only. Once the limiting reactant is determined one must use the given mole values of the limiting reactant to solve problem. That is ...

Limiting reactant determination:

              Cu°          +    2 AgNO₃  => Cu(NO₃)₂ + 2Ag°

Cu: 7.28 / 1  = 7.28

AgNO₃ : 7.28 / 2 = 3.64 => Limiting Reactant is AgNO₃

Solving Problem depends on AgNO₃; Cu will be in excess.

Since coefficients of AgNO₃ & Ag° are equal, then the moles AgNO₃ used equals moles Ag° produced and is therefore 7.28 moles Ag°.

5 0
2 years ago
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