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3 years ago

What does a catalyst do when added to a chemical reaction? Select all that apply.

Chemistry

2 answers:

Darina [25.2K]3 years ago

8 0

Answer:

$\boxed {\boxed {\sf It \ lowers \ the \ activation \ energy \ and \ it \ speeds \ up \ chemical \ reactions }}$

Explanation:

A catalyst is a substance that <u>increases the rate</u> of a chemical reaction. Some examples are enzymes and acid-base catalysts.

They can do this by <u>lowering activation energy</u> (the energy needed to undergo a reaction) or modifying a certain mechanism in the reaction.

Catalysts are unique because they aren't consumed or used up in a reaction. They can be reused many times.

So, based on the information above, catalysts do not increase the activation energy or get consumed in the reaction. That leaves two correct answers: they lower the activation energy and speed up chemical reactions.

Stels [109]3 years ago

7 0

Answer:

It increases the activation energy.

It speeds up chemical reactions.

Explanation:

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The combustion of carbohydrates and the combustion of fats are both exothermic processes, yet the combustion of carbohydrates is

saveliy_v [14]

Explanation:

Combustion of a compound is the reaction with oxygen , hence , the process of combustion is an oxidation reaction.

The carbohydrates contain more amount of oxygen as compared to the fats ,

Hence ,

carbohydrates , have a lot of oxygen contents , are are already partially oxidized , but fats have lower oxygen content .

Therefore ,

The partially oxidized carbohydrates are very difficult to oxidized in comparison to fats .

4 0

3 years ago

Acetic acid is a weak acid with a pKa of 4.76. What is the concentration of acetate in a buffer solution of 0.2M at pH 4.9. Give

Ghella [55]

Answer:

$[base]=0.28M$

Explanation:

Hello,

In this case, by using the Henderson-Hasselbach equation one can compute the concentration of acetate, which acts as the base, as shown below:

$pH=pKa+log(\frac{[base]}{[acid]} )\\\\\frac{[base]}{[acid]}=10^{pH-pKa}\\\\\frac{[base]}{[acid]}=10^{4.9-4.76}\\\\\frac{[base]}{[acid]}=1.38\\\\$

$[base]=1.38[acid]=1.38*0.20M=0.28M$

Regards.

6 0

3 years ago

Burning 12.00 g of an oxoacid produces 17.95 g of carbon dioxide and 4.87 g of water. Consider that 0.25

Veseljchak [2.6K]

Answer: The molecular formula will be $C_6H_6O_6$

Explanation:

Mass of $CO_2$ = 17.95 g

Mass of $H_2O$ = 4.87 g

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 17.95 g of carbon dioxide, = $\frac{12}{44}\times 17.95=4.89g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 4.87 g of water, = $\frac{2}{18}\times 4.87=0.541g$ of hydrogen will be contained.

Mass of oxygen in the compound = (12.00) - (4.89+0.541) = 6.57 g

Mass of C = 4.89 g

Mass of H = 0.541 g

Mass of O = 6.57 g

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{4.89g}{12g/mole}=0.407moles$

Moles of H= $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{0.541g}{1g/mole}=0.541moles$

Moles of O= $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{6.57g}{16g/mole}=0.410moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{0.407}{0.407}=1$

For H = $\frac{0.541}{0.407}=1$

For O = $\frac{0.410}{0.407}=1$

The ratio of C : H : O = 1: 1 : 1

Hence the empirical formula is $CHO$ .

Hence the empirical formula is $CHO$

The empirical weight of $CHO$ = 1(12)+1(1)+1(16)= 29 g.

If 0.25 moles has mass of 44.0 g

Thus 1 mole has mass of = $\frac{44.0}{0.25}\times 1=176g$

Thus molecular mass is 176 g

Now we have to calculate the molecular formula.

$n=\frac{\text{Molecular weight }}{\text{Equivalent weight}}=\frac{176g}{29g}=6$

The molecular formula will be= $6\times CHO=C_6H_6O_6$

5 0

3 years ago

Why do you think the different heating process result in different softness or hardness of the steel? Think about what steel is

ale4655 [162]

Explanation:

Different heating process affect the microstructure of the steel in different ways. Thus, imparting different properties to the steel. For example, annealing is done is done to impart softness to steel, hardening is done to hardened the steel( eg: carburizing, nitriding, cyaniding) whereas tempering is done to improve the ductility of the steel.

Steel mainly contains iron and carbon. This percentage of carbon and iron decides the property of the steel. It is the % of carbon which is altered in different heating process that to obtained the desire microstructure in steel.

8 0

3 years ago

Suppose a 1.0 L solution contains 0.020 M in Cu(NO3)2, then 0.40 moles of NH3 are added. Assuming no change in volume, what is t

Rasek [7]

Answer:

$4.6*10^{-14}$ M