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3 years ago

Why do experiments need to be repeatable?

2 answers:

5 0

They need to be repeatable to prove that results from the expirement are viable, that it didn't just happen because of a series of things outside of the scientists control. Repetition just makes the expirement seem more credible.

maw [93]3 years ago

3 0

If they were not repeatable people would think the experiment is not accurate. If it can be repeated than the data can prove a very valid point.

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Use the provided reduction potentials to calculate ArGº for the following balanced redox reaction: Pb2+(aq) + Cu(s) → Pb(s) + Cu

nydimaria [60]

Answer : The correct option is, +91 kJ/mole

Solution :

The balanced cell reaction will be,

$Cu(s)+Pb^{2+}(aq)\rightarrow Cu^{2+}(aq)+Pb(s)$

Here copper (Cu) undergoes oxidation by loss of electrons, thus act as anode. Lead (Pb) undergoes reduction by gain of electrons and thus act as cathode.

First we have to calculate the standard electrode potential of the cell.

$E^0_{[Pb^{2+}/Pb]}=-0.13V$

$E^0_{[Cu^{2+}/Cu]}=+0.34V$

$E^0_{cell}=E^0_{cathode}-E^0_{anode}$

$E^0_{cell}=E^0_{[Pb^{2+}/Pb]}-E^0_{[Cu^{2+}/Cu]}$

$E^0_{cell}=-0.13V-(0.34V)=-0.47V$

Now we have to calculate the standard Gibbs free energy.

Formula used :

$\Delta G^o=-nFE^o_{cell}$

where,

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

n = number of electrons = 2

F = Faraday constant = 96500 C/mole

$E^o$ = standard e.m.f of cell = -0.47 V

Now put all the given values in this formula, we get the Gibbs free energy.

$\Delta G^o=-(2\times 96500\times (-0.47))=+90710J/mole=+90.71kJ/mole\approx +91kJ/mole$

Therefore, the standard Gibbs free energy is +91 kJ/mole

6 0

3 years ago

What is the molarity of a solution in which 25g NaCl in a 2.00 L solution?

Paladinen [302]

Mass of sodium :- 23 grams

Mass of Chlorine :- 35.5 grams

Mass of NaCl :- 58.5 grams

mass given :- 25 grams

moles :- 0.432 ( given mass/ ionic mass)

$molarity = \frac{moles}{vol} \\ molarity = \frac{0.432}{2} \\ molarity = 0.216 \: mole{l}^{ - 1} or \: molar$

5 0

2 years ago

What type of wave do the contractions of the snake muscles make as the snake moves forward

S_A_V [24]

Actually, there are four kinds of reptile motion:

Concertina - vermiform. Circular muscles around the snake squeeze the front of the snake's body out long, then the latter half is pulled forward.

Rectilinear crawling - Belly scutes are moved forward individually in a wave-like motion.

Side-winding - Snake's version of "walking". Use by several species to move over fluidic substrates, such as sand.

Lateral undulation - Most common form of movement. Snake presses on alternating pressure points to force body forward (or backward)

(taken from a user on Yahoo from Correct Answers)

3 0

3 years ago

Do the same volumes of H2O and H2SO4 have the same number of molecules?

Romashka [77]

No, they do not. Hope I helped! :)

5 0

3 years ago

What does an emission spectrum show?

IrinaVladis [17]

It shows the type of atoms/elements in a substance

Different types of atoms have different emission spectrum - a concept supported by Bohr quantum theory - hence one is able to identify elements in a substance using a method called spectroscopy.

Explanation:

When an electron jumps from a low energy orbital to a higher energy orbital in an atom, it absorbs a specific wavelength of electromagnetic radiation (This is called absorption spectrum). Vice versa, if the same electron jumps from a higher to a lower energy orbital it releases the equivalent quantum energy in electromagnetic wave (This is called emission spectrum). Different types of atoms of different elements have a unique spectrum identifier.

Learn More:

Learn more about spectroscopy;

brainly.com/question/3822641

brainly.com/question/13435562

#LearnWithBrainly

3 0

3 years ago