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vladimir2022 [97]
3 years ago
15

Which is the dependent variable in an experiment? 1.what I observe. 2. what I keep the same 3.What I change in the experiment. H

ELP NOW​
Chemistry
1 answer:
shtirl [24]3 years ago
3 0

Answer:

1.what I observe.

Explanation:

The dependent variable in an experiment is what is being observed in the experimental procedure.

This variable is the one that is closely tied to the effects originating from changing the independent variables.

  • Independent variables are the ones that cause the observation being studied.
  • The effects produced and then studied are the dependent variables.
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"Thermite" reactions have been used for welding metal parts such as railway rails and in metal refining. One such thermite react
frosja888 [35]

<u>Answer:</u> The given reaction is non-spontaneous in nature.

<u>Explanation:</u>

Entropy change is defined as the difference in entropy of all the product and the reactants each multiplied with their respective number of moles.

The equation used to calculate entropy change is of a reaction is:

\Delta S^o_{rxn}=\sum [n\times \Delta S^o_{(product)}]-\sum [n\times \Delta S^o_{(reactant)}]

For the given chemical reaction:

3Mg(s)+Cr_2O_3(s)\rightarrow 3MgO(s)+2Cr(s)

The equation for the entropy change of the above reaction is:

\Delta S^o_{rxn}=[(3\times \Delta S^o_{(MgO(s))})+(2\times \Delta S^o_{(Cr(s))})]-[(3\times \Delta S^o_{(Mg(s))})+(1\times \Delta S^o_{(Cr_2O_3(s))})]

We are given:

\Delta S^o_{(Mg(s))}=32.68J/K.mol\\\Delta S^o_{(Cr_2O_3(s))}=81.2J/K.mol\\\Delta S^o_{(MgO(s))}=26.94J/K.mol\\\Delta S^o_{(Cr(s))}=23.77J/K.mol

Putting values in above equation, we get:

\Delta S^o_{rxn}=[(3\times (26.94))+(2\times (23.77))]-[(3\times (32.68))+(1\times (81.2))]\\\\\Delta S^o_{rxn}=-50.88J/K=-0.0509kJ/K.mol

For the reaction to be spontaneous, the Gibbs free energy of the reaction must come out to be negative.

To calculate the standard Gibbs free energy of the reaction, we use the equation:

\Delta G^o=\Delta H^o-T\Delta S^o

where,

\Delta G^o = standard Gibbs free energy = ?

\Delta H^o = standard enthalpy change of the reaction = 665.1 kJ/mol

T = Temperature = 298.15 K

\Delta S^o = standard entropy change of the reaction = -0.0509 kJ/K.mol

Putting values in above equation, we get:

\Delta G^o=(665.1kJ/mol)-(298.15K\times (-0.0509kJ/K.mol))=680.27kJ/mol

As, the Gibbs free energy of the reaction is coming out to be positive, the reaction is non-spontaneous in nature.

Hence, the given reaction is non-spontaneous in nature.

4 0
4 years ago
Please help again. Sorry!&gt;♡
Svet_ta [14]

Matter is found every where in the universe and there is never any substance in the universe that is not composed of matter.

<h3>What is matter?</h3>

Matter is anything that has weight and occupy space. We know that matter is present in every part of the universe. Everything in the universe is composed of matter. Matter forms the basics of our study of the universe. Water, food cloths everything all are composed of matter.

The fact that matter inundates the universe has made the study of matter an unavoidable topic. As such, we can not really be able to point something that is of made up of matter. There can be no such thing!

As long as a thing does exist in the material universe, that thing is made up of matter. Look at yourself for example, matter is spread all across your body. The same occurs in the bodies of every other living thing.

The nonliving things are not also left out as they are equally composed of diverse kinds of matter that exists in the universe.

Learn more about matter:brainly.com/question/28487167

#SPJ1

8 0
2 years ago
Which is not one of the parts of the cell theory.
alekssr [168]

Answer:

Pretty sure the answer is d) cells come from nonliving objects

Explanation:

i just think i remember xd

7 0
3 years ago
Write down the formula for B<br> example:<br> Hydrogen + Fluorine = Hydrogen Fluorine <br><br> help
Tom [10]

Answer:

P³⁻ + Cl⁻ --> PCl₃

Explanation:

PCl₃: phosphorus trichloride. prefix in front of chloride is "tri"–meaning three.

5 0
3 years ago
Read 2 more answers
One of the main advantages of Hydrogen as a fuel is that:
weqwewe [10]

Answer:

The correct answer is option D.

Explanation:

A fuel cell is defined as the electrochemical cell which converts the chemical energy of a fuel (often used hydrogen) and an oxidizing agent (often used oxygen) into electrical energy via a pair of redox reactions.

The reactions which occur in hydrogen-oxygen fuel cell are:

At cathode:  H_2+2OH^-\rightarrow 2H_2O+2e^-

At anode:  \frac{1}{2}O_2+H_2O+2e^-\rightarrow 2OH^-

As we can see that reaction of hydrogen gas with oxygen gas gives us the water as a product which can be used for other things and it also doesn't pollutes environment.

6 0
4 years ago
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