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Deffense [45]
3 years ago
7

. An aqueous solution ‘A’ turns phenolphthalein solution pink. On addition of an aqueous solution ‘B’ to ‘A’, the pink colour di

sappears. The following statement is true for solution ‘A’ and ‘B’
(i) A is strongly basic and B is a weak base.
(ii) A is strongly acidic and B is a weak acid.
(iii) A has pH greater than 7 and B has pH less than 7
(iv) A has pH less than 7 and B has pH greater than 7
Chemistry
1 answer:
lara31 [8.8K]3 years ago
8 0

Answer:

(iii) A has pH greater than 7 and B has pH less than 7

Explanation:

Phenolphthalein is a common indicator in acid base titrations. It turns pink in basic conditions and turns colorless in acidic conditions. Thus on addition of solution A it becomes pink so A should be basic having pH more than 7. On addition of B , it turn out to be colorless means that B is an acidic solution having pH less than 7.

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Recall that the value of Kw for the autoionization of water varies with temperature. At the temperature of your body (37°C), Kw
kvasek [131]

Answer:

pH =6.70

Explanation:

When Kw = 1x10^-14

[H3O+] = [OH-] --> 1x10-7

Kw =3.98x^10-14

3.98x^10-14 = [H3O+] . [OH-]

√ (3.98x^10-14) =  [H3O+] = [OH-]

[H3O+] = 1.99×10^-7

- log [H3O+] = pH ---> -log 1.99x10^-7 = 6.70

5 0
3 years ago
Use the combustion of methanol to calculate
sergey [27]

Answer:

4.18 kJ / 6.55x10-3 mol = 638.6 kJ/mol = experimental ΔHC kJ/mol methanol.

Explanation:

4 0
3 years ago
Which factors are used to calculate the connetic energy of an object?
lora16 [44]
<span>You can use physics to calculate the kinetic energy of an object. When you start pushing or pulling a stationary object with a constant force, it starts to move if the force you exert is greater than the net forces resisting the movement, such as friction and gravity. If the object starts to move at some speed, it will acquire kinetic energy.So how do you calculate kinetic energy?A force acting on an object that undergoes a displacement does work on the object. If this force is a net force that accelerates the object (according to Newton’s second law), then the velocity changes due to the acceleration. The change in velocity means that there is a change in the kinetic energy of the object.The change in kinetic energy of the object is equal to the work done by the net force acting on it. This is a very important principle called the <span>work-energy theorem. </span>After you know how work relates to kinetic energy, you’re ready to take a look at how kinetic energy relates to the speed and mass of the object.The equation to find kinetic energy,<span> KE,</span> is the following, where m is mass and v is velocity:Using a little math, you can show that work is also equal to (1/2)mv2. Say, for example, that you apply a force to a model airplane in order to get it flying and that the plane is accelerating. Here’s the equation for net force:F = maThe work done on the plane, which becomes its kinetic energy, equals the following:Net force F equals mass times acceleration. Assume that you’re pushing in the same direction that the plane is going; in this case, cos 0 degrees = 1, soW = Fs = masAssuming constant acceleration, you can tie this equation to the final and original velocity of the object. Use the equationwhere<span> v</span>f equals final velocity and vi equals initial velocity. Solving for a gives youIf you plug this value of a into the equation for work, W = <span>mas, </span>you get the following:If the initial velocity is zero, you getThis is the work that you put into accelerating the model plane — that is, into the plane’s motion — and that work becomes the plane’s kinetic energy, KE:This is just the work-energy theorem stated as an equation.You normally use the kinetic energy equation to find the kinetic energy of an object when you know its mass and velocity. Say, for example, that you’re at a firing range and you fire a 10-gram bullet with a velocity of 600 meters/second at a target. What’s the bullet’s kinetic energy? Using the equation to find kinetic energy, you simply plug in the numbers, remembering to convert from grams to kilograms first to keep the system of units consistent throughout the equation:</span><span>The bullet has 1,800 joules of energy, which is a lot of energy to pack into a 10-gram bullet.

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3 0
3 years ago
ANSWERRRRRRRRRRRRRRR PLEASEEEEEEEEEEEEEEEEEEEEEEEEEEEEEREEEEEEE
MAXImum [283]

Answer:

The 2nd choice correctly models a longitudinal wave. (I attached a pic)

Explanation:

It starts off compression and next is rarefaction. It then continues to go back and forth between the two.

Hope that helps!!

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4 0
3 years ago
Picture of 2010 Todd Abronowitz Gas Laws problems, super fun if you’re in AP chem. Can you help a pre-AP struggling student out
exis [7]

Answer:

1. 0.422 atmospheres

2. 633281.25 Pascals

3. (a) Move up

(b) 868 mmHg

4. 868 mmHg

5. 775 mmHg

6. Partial pressure of He is 0.64 atm.

Partial pressure of oxygen is 1.29 atm.

Partial pressure of N is 2.57 atm.

7. 445.72 torr.

Explanation:

1. To convert 321  torr to atmospheres

1  atmosphere = 760 torr

∴ 1 torr = 1/760 atmospheres

Hence, 321 torr = 321 × 1/760 = 321/760 atmospheres = 0.422 atmospheres

2. To convert 6.25 atmospheres to Pascals, we have;

1 atmosphere = 101325 Pascals

∴ 6.25 atmospheres = 6.25 × 101325 Pascals = 633281.25 Pascals

3. (a) Here we have, given that the value of the pressure on the bottle = 830 mmHg, when the valve is opened, the mercury in the open-end arm will move up because the pressure of the gas inside the flask is more than the pressure on the other side of the open-end arm

(b) After the mercury stops moving the difference between the two columns will be the difference between the two pressures, that is 830 mmHg - 745 mmHg = 85 mmHg

4. From the diagram, it is seen that the differenc beteen the two columns is 123 mm, therefore, the pressure in the flask is 123 mmHg more than the external pressure, hence the pressure of the as in the flask = 745 mmHg + 123 mmHg = 868 mmHg

5. Here we have that the height of the mercury in the open-end is less than the height of the mercury on the arm closer to the flask, therefore, the pressure of the gas in the flask = 825 mmHg - 50 mmHg = 775 mmHg

6. Number of moles of He = 1 mole

Number of moles of oxygen, O = 2 mole

Number of moles of nitrogen, N = 4 mole

From Dalton's law of partial pressure we have that, the total pressure of a given mass of gas is equal to the partial pressure of the individual gases

That \ is \ \chi _i = \frac{n_i}{n_{total}} \ and \ P_i = \chi_i \cdot P_{total}

Hence;

Total number of moles = 1 + 2 + 4 = 7 moles

Mole fraction of He = 1/7

Partial pressure of He = 1/7×4.5 = 0.64 atm.

Mole fraction of oxygen, O = 2/7

Partial pressure of oxygen= 2/7×4.5 = 1.29 atm.

Mole fraction of N = 4/7

Partial pressure of N = 4/7×4.5 = 2.57 atm.

7. From Boyle's law

P₁×V₁ = P₂×V₂

Hence;

P₂ = P₁×V₁/V₂

Where:

P₁ = Initial pressure = 2.57 atm

V₁ = Initial volume =1.57 liters

V₂ = New volume = 6.88 liters

P₂ = New pressure = 2.57×1.57/6.88  = 0.59 atm.

To convert 0.59 atm. to torr, we multiply by 760 thus;

0.59 atm. = 0.59 × 760 torr = 445.72 torr.

5 0
3 years ago
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