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2 years ago

The indicator phenolphthalein is added to the _____________.

Chemistry

1 answer:

bonufazy [111]2 years ago

6 0

The indicator, phenolphthalein is added to the analyte as an indicator in acid–base titrations.

Phenolphthalein is a color changing indicator for acid base titrations.

Titration is a quantitative technique used to find concentration of an unknown solution(analyte ) from a solution of known concentration. which is the titrant.

Now the procedure is set up that, the titrant is in the burette and added to the analyte with known volume)in a conical flask in the presence of an indicator till the endpoint of the reaction.

This is marked by a sharp change of color to explain the point when the titrant neutralizes the analyte solution.(phenolphthalein is colorless in acidic solutions but turns pink in basic solutions).

See more here:brainly.com/question/22790616

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An endergonic reaction with a Δh and Δs can be changed into an exergonic reaction.

zheka24 [161]

Full question:

This question is incomplete, here it is completed:

An endergonic reaction with a ______ ∆H and a ______ ∆S can be changed into an exergonic reaction by decreasing the temperature.

Option A: negative, positive

Option B: negative, negative

Option C: positive, positive

Option D: positive, negative

Answer:

Option B: negative, negative

Explanation:

The change in free energy (ΔG) of a system for a constant-temperature process is

ΔG = ΔH - TΔS

free energy is the energy available to do work. Thus, if a particular reaction is accompanied by a release of usable energy (that is, ΔG is negative), it is said to be exergonic. On the other hand, if a reaction consumes energy (that is, ΔG is positive), it is said to be endergonic.

Looking at the equation, we can see that if ΔH is negative and ΔS is negative, then ΔG will be negative only when TΔS is smaller in magnitude than ΔH. This condition is met when T is small.

ΔG = ΔH - TΔS

- -

This means that the reaction proceeds spontaneously at low temperatures. At high temperatures, the reverse reaction becomes spontaneous. An example of that would be the following reaction:

NH₃(g) + HCl(g) → NH₄Cl(s)

4 0

3 years ago

A 45-g aluminium spoon(specific heat 0.80 / J/gdegree Celsius) at 24 degree celsius is placed in 180 ml(180 grams) of coffee at

Vlad [161]

Explanation:

a) The amount of heat released by coffee will be absorbed by aluminium spoon.

Thus, $heat_{absorbed}=heat_{released}$

To calculate the amount of heat released or absorbed, we use the equation:

$Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})$

Also,

$m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)]$ ..........(1)

where,

q = heat absorbed or released

$m_1$ = mass of aluminium = 45 g

$m_2$ = mass of coffee = 180 g

$T_{final}$ = final temperature = ?

$T_1$ = temperature of aluminium = $24^oC$

$T_2$ = temperature of coffee = $85^oC$

$c_1$ = specific heat of aluminium = $0.80J/g^oC$

$c_2$ = specific heat of coffee= $4.186 J/g^oC$

Putting all the values in equation 1, we get:

$45 g\times 0.80J/g^oC\times (T_{final}-24^oC)=-[180 g\times 4.186J/g^oC\times (T_{final}-83^oC)]$

$T_{final}=80.30^oC$

80.30 °C is the final temperature.

b) Energy flows from higher temperature to lower temperature.Whenever two bodies with different energies and temperature come in contact. And the resulting temperature of both bodies will less then the body with high temperature and will be more then the body with lower temperature.

So, is our final temperature of both aluminium and coffee that is 80°C less than initial temperature of coffee and more than the initial temperature of the aluminum.

8 0

3 years ago

what happens when baking soda is mixed with vinegar a a new substance is formed B the substances are the same c but the baking s

Ray Of Light [21]

Answer:

NaHCO3 sodium bicarbonate is baking soda; added to the acetic acid, it forms sodium acetate (aqueous), CO2 gas & water. Remove the water & solid sodium acetate remains.

Explanation:

5 0

4 years ago

What is true of saturated fatty acids?

Natali5045456 [20]

Answer:

The second answer, because when something saturated, it has the maximum possible number of hydrogen atoms.

7 0

3 years ago

Read 2 more answers

HELP! URGENTLY NEEDED! I NEED THIS ANSWER IN 5 MINUTES AND PERSON WHO HELPS GET THE ANSWER RIGHT GETS 25 POINTS!!! PLEASE I AM F

marishachu [46]