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Gre4nikov [31]
3 years ago
14

A 1.00 cm2 blackbody surface emits 201 watts of radiant power. What is the temperature of the surface? Give to the nearest whole

degree.
Chemistry
1 answer:
erastovalidia [21]3 years ago
7 0

Explanation:

Formula for black body radiation is as follows.

                 \frac{P}{A} = \sigma \times T^{4} J/m^{2}s

where,       P = power emitted

                 A = surface area of black body

          \sigma = Stephen's constant = 5.6703 \times 10^{-8} watt/m^{2}.K^{-4}

As area is given as 1.0 cm^{2}. Converting it into meters as follows.

           1.00 cm^{2} \times \frac{(10^{-2})^{2} m^{2}}{1 cm^{2}}      (as 1 m = 100 cm)

            = 1 \times 10^{-4} m^{2}

It is given that P = 201 watts. Hence,  

       \frac{201 watts}{1 \times 10^{-4} m^{2}} = 5.6703 \times 10^{-8} watt/m^{2}.K^{-4} \times T^{4}

                T^{4} = 35.45 \times 10^{12}

                       T = (35.45 \times 10^{12})^{1/4}

                          = 8862.5 K

Thus, we can conclude that the temperature of the surface is 8862.5 K.

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Explain how Archimedes' principle determines the buoyant force on an object<br> in any fluid medium.
gladu [14]

Answer:

<em>An object in a fluid medium displaces a set amount of fluid upon immersion. Archimedes' principle states that the weight of the displaced fluid is equal to the buoyant force exerted on the object</em>

6 0
3 years ago
Explain the similarities and differences between putting a beaker of ethanoic acid in the refrigerator and mixing it with sodium
frez [133]

Answer:

See explanation

Explanation:

When a beaker of ethanoic acid is placed in the refrigerator, its temperature drops and the vessel feels cool.

Now, when we mix ethanoic acid and sodium carbonate, an endothermic reaction occurs, fizzing is observed as carbon dioxide is given off and heat is lost to the surroundings causing the reaction vessel to feel cool to touch.

The difference between putting ethanoic acid in the refrigerator and adding  sodium carbonate to the solution is that, in the former, no new substance is formed. The substance remains ethanoic acid when retrieved from the refrigerator. In the later case, new substances are formed. The substance is no more ethanoic acid because a chemical reaction has taken place.

5 0
2 years ago
15.0 g of Fe and 25.0 g of sand are added to 250.0 g of water. a. Determine the percent mass of Fe, sand, and water in the mixtu
lana [24]

Answer:

A. percentage mass of iron = 5.17%

percentage mass of sand  = 8.62%

percentage mass of water = 86.205%

B. (Iron + sand + water) -------> ( iron + sand) ------> sand

C. The step of separation of iron and sand

Explanation:

A. Percentage mass of the mixtures:

Total mass of mixture = (15.0 + 25.0 + 250.0) g =290.0 g

percentage mass of iron = 15/290 * 100% = 5.17%

percentage mass of sand = 25/290 * 100% = 8.62%

percentage mass of water = 250/290 * 100% = 86.205%

B. Flow chart of separation procedure

(Iron + sand + water) -------> separation by filtration using filter paper and funnel to remove water --------> ( iron + sand) -----------> separation using magnet to remove iron ------> sand

C. The step of separation of iron and sand by magnetization of iron will have the highest amount of error because during the process, some iron particles may not readily be attracted to the magnet as they may have become interlaced in-between sand grains. Also, some sand particle may also be attracted to the magnet as they are are borne on iron particles.

5 0
3 years ago
A3. Answer each of the following: A student dissolved 1.3g of Ba(OH)2 (molar mass = 171.34 g/mol) in 250 mL of water and reacted
Sunny_sXe [5.5K]

Answer:

(i) Ba(OH)2 + 2 HNO3 → Ba(NO3)2 + 2 H2O

(ii) 121.392 mL of HNO3 0.125M are required to react completely with the Ba(OH)2 solution.

(iii) The molarity of the Ba(OH)2 solution is 0.0303 M

(iv) Bromothymol Blue (pH range 6.0 - 7.6)

(v) pH of the soultion would be 2.446

Explanation:

(i) First of all, to solve this problem we should write the balanced chemical equation to know the stoichiometry of the reaction:

Ba(OH)2 + HNO3 → Ba(NO3)2 + H2O

The previous reaction simply describes the reactants and products involved in the chemical process. As you can see, the mass balance is not balanced because the quantity of atoms in the reactants side of the equation is not equal to the ones in the products side. So we try to add coefficients to the reaction in order to balance the amount of atoms on both sides of the reaction. To to this, we take a look at the reaction: We see that the main product formed Ba(NO3)2 has 2 atoms of N, so we add a number 2 besides the HNO3 to equal the quantity of Nitrogen atoms:

Ba(OH)2 + 2 HNO3 → Ba(NO3)2 + H2O

Now, we can see that from the reactants side of the equation there are 8 atoms of Oxygen and in the products side we only have 7. Hence, we add the number 2 besides the molecule of water:

Ba(OH)2 + 2 HNO3 → Ba(NO3)2 + 2 H2O

If we check the situation now, we can observe that all the atoms are balanced on both sides of the reaction, so We did it!

(ii) From the balanced equation we now know that 1 mole of Ba(OH)2 reacts with 2 moles of HNO3 to form the stated products. Let's see, therefore, how many moles of Ba(OH)2 are in solution:

According to the molar mass of Ba(OH)2: 1 mole = 171.34 g

So, the student add 1.3 g of the compound to water. This means that he added 7.587x10-3 moles of Ba(OH)2. This amount of Ba(OH)2 will react with 0.01517 moles of HNO3 taking into account the stoichiometry of the balanced equation described above (1 mol of Ba(OH)2 reacts with 2 moles of HNO3).

Now that we know the amount of moles of acid required to react with the hydroxide, we need to translate this moles into volume of acid solution:

We have a 0.125 M HNO3 solution. This means that there are 0.125 moles of HNO3 in 1000 ml of solution.

0.125 moles HNO3 ------ 1000 ml Solution

0.01517 moles --------- x = 121.392 ml HNO3 Solution

This means that we need 121.392 ml of a 0.125 M HNO3 solution to react completely with the Ba(OH)2 added by the student.

(iii) Now we are asked to calculate the molarity of the Ba(OH)2 solution. From the calculations performed before in point (ii) we know that the hydroxide solution consisted of 7.587x10-3 moles of Ba(OH)2 and that this quantity of moles were in 250 mL of water. So:

250 ml Solution ----- 7.587 x10-3 moles Ba(OH)2

1000 ml Solution ----- x = 0.0303 M

(iv) Since Ba(OH)2 and HNO3 are both strong base and acid respectively, they react with each other completely to form the salt Ba(NO3)2 and water. Therefore, the pH of the solution when the reactions ends will be neutral or nearly neutral (pH = 7) and because of this we need an indicator that would change its color around this pH to be able to visualize the end point of the titration. The Bromothymol blue serves this perfectly since its change in color ranges between pH 6.0 and 7.6.

(v) If we now calculate how many moles of HNO3 are present in 150 mL of a 0.125 M solution we obtain:

1000 mL solution ---- 0.125 moles HNO3

150 mL solution ------ x = 0.01875 moles.

From this, we know that if we add 150 mL of the acid solution we would have 0.01875 moles of HNO3. However, from the previous points, we know that 0.01517 moles of the compound will be consumed by the reaction with Ba(OH)2 leaving in solution only 3.58 x10-3 moles of HNO3 (0.01875 moles - 0.01517 moles).

This amount of HNO3 will dissociate according to the following equation:

HNO3 → H+ + NO3-

The amount of protons present in solution will determine the pH. Because, as we said before, Nitric acid is a strong acid, it will dissociate completely intro protons and nitrate. As a result of this, we would have 3.58 x10-3 moles of H+ in the solution (1 mole of HNO3 produces 1 mole of H+) and considering the contribution of protons in the solution given by the dissociation of the water negligible, then:

pH = - log [H+]

pH = - log [3.58 x10-3] = 2.446

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Answer:

It’s b even check quizzes

Explanation:

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