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3 years ago

What is a control group and is it always needed in an experiment?

Chemistry

1 answer:

bagirrra123 [75]3 years ago

3 0

Answer:

yes, it is always needed

Explanation:

a control group is what you choose to control in an expirement its the amount of somthing you don't change

Hope this helped

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Calculate the standard cell potential of the following cell at 25°C. Sn(s) | Sn2+(aq) || Cu2+(aq) | Cu(s).

Semmy [17]

Answer:

0.48 V

Explanation:

Usually in the cell notation, the left side shows oxidation. So,

Oxidation half reaction:

$Sn_{(s)}\rightarrow Sn^{2+}_{(aq)}+2e^-$ $E^o_{ox}=-E^o_{red}=-(-0.14\ V)=0.14\ V$

Reduction half reaction:

$Cu^{2+}_{(aq)}+2e^-\rightarrow Cu_{(s)}$ $E^o_{red}=0.34\ V$

$E^o_{cell}=E^o_{ox}+E^o_{red}= (0.14+0.34)\ V=0.48\ V$

4 0

3 years ago

A welding torch produces a flame by burning acetylene fuel in the presence of oxygen. This flame is used to melt a metal. Which

NISA [10]

Answer:

chemical energy into thermal energy

Explanation:

The reaction taking place is as follows

2C₂H₂ + 5O₂ = 4CO₂ + 2H₂O + Heat

In this reaction bonds present in acetylene is broken and new bond present in water and carbon dioxide are formed . In the whole process of bond breaking and bond formation , there is net loss of energy and that energy is released as heat energy .

Thus we can say that in the whole process , chemical energy is converted into heat energy .

5 0

3 years ago

If 45.0 mL of ethanol (density = 0.789 g/mL) initially at 8.0 ∘C is mixed with 45.0 mL of water (density = 1.0 g/mL) initially a

strojnjashka [21]

Answer : The final temperature of the mixture is, $22.14^oC$

Explanation :

First we have to calculate the mass of ethanol and water.

$\text{Mass of ethanol}=\text{Density of ethanol}\times \text{Volume of ethanol}=0.789g/mL\times 45.0mL=35.5g$

and,

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1.0g/mL\times 45.0mL=45.0g$

Now we have to calculate the final temperature of the mixture.

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

$q_1=-q_2$

$m_1\times c_1\times (T_f-T_1)=-m_2\times c_2\times (T_f-T_2)$

where,

$c_1$ = specific heat of ethanol = $2.42J/g^oC$

$c_2$ = specific heat of water = $4.18J/g^oC$

$m_1$ = mass of ethanol = 35.5 g

$m_2$ = mass of water = 45.0 g

$T_f$ = final temperature of mixture = ?

$T_1$ = initial temperature of ethanol = $8.0^oC$

$T_2$ = initial temperature of water = $28.6^oC$

Now put all the given values in the above formula, we get:

$35.5g\times 2.42J/g^oC\times (T_f-8.0)^oC=-45.0g\times 4.18J/g^oC\times (T_f-28.6)^oC$

$T_f=22.14^oC$

Therefore, the final temperature of the mixture is, $22.14^oC$

3 0

3 years ago

Which one of the following is not an agent of chemical weathering?

irakobra [83]

Answer:

its proprionic acid which do not cause any hazardous effect on environment it only effect internal body of human if it is ingested.

Explanation:

7 0

2 years ago

If oxygen is removed from a sample of air as iron rust, what happens to the particle pressure of oxygen in the air?

klasskru [66]

Answer : It increases

Rusting is where oxygen binds to iron and forms iron oxide.

So once iron rusts, there is oxygen, just not in air; it's in the iron oxide.

All reactions are reversible, albeit at different rates (the "irreversible" ones are still reversible, but much slower given that they take so much collision luck and energy.

5 0

3 years ago