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2 years ago

11

Runoff from agricultural land carries chemicals from fertilizers that collect in a lake. The buildup of chemicals can eventually

cause:.

1 answer:

bagirrra123 [75]2 years ago

5 0

Answer:

what are the roles of minerals in maintaning homeostasis?

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A cylinder contains 250 g of Helium at 200 K. The external pressure is constant at 1 atm. The temperature of the system is raise

Black_prince [1.1K]

Answer:

There is 96200 J or 96 kJ of heat released.

Explanation:

<u>Step 1: </u>Data given

Mass of helium = 250 grams

Temperature = 200 K

Temperature is raised by 74 K

The heat capacity of helium = 20.8 J/mol*K

Molecular weight for helium = 4 g/mol

<u>Step 2:</u> Calculate moles of Helium

Moles of Helium = mass of Helium / molar mass of helium

Moles of helium = 250 grams / 4g/mol

Moles of helium = 62.5 moles

<u>Step 3:</u> Calculate heat

Q = n*c*ΔT or

⇒ with Q = the heat released in Joule

⇒ with n = moles of helium = 62.5 moles

⇒ with c = the heat capacity of helium = 20.8 J/mol*K

⇒ with ΔT = the change in temperature = T2 - T1 = 74 K

Q = 62.5 mol * 20.8 J/mol*K * 74 K

Q = 96200 J = 96 kJ

Since the temperature is raised, this is an exothermic reaction. The heat is released.

There is 96200 J or 96 kJ of heat released.

8 0

3 years ago

Mr. Ragusa asks Hassan to make silver crystals from the following reaction.

SVEN [57.7K]

Answer:

Percentage yield = 61.7%

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated:

2AgNO₃ + Cu —> Cu(NO₃)₂ + 2Ag

Next, we shall determine the mass of AgNO₃ that reacted and the mass of Ag produced from the balanced equation. This is illustrated below:

Molar mass of AgNO₃ = 108 + 14 + (16×3)

= 108 + 14 + 48

= 170 g/mol

Mass of AgNO₃ from the balanced equation = 2 × 170 = 340 g

Molar mass of Ag = 108 g/mol

Mass of Ag from the balanced equation = 2 × 108 = 216 g

SUMMARY:

From the balanced equation above,

340 g of AgNO₃ reacted to produce 216 g of Ag.

Next, we shall determine the theoretical yield of Ag. This can be obtained as follow:

From the balanced equation above,

340 g of AgNO₃ reacted to produce 216 g of Ag.

Therefore, 51 g of AgNO₃ will react to produce = (51 × 216)/340 = 32.4 g of Ag.

Thus, the theoretical yield of Ag is 32.4 g.

Finally, we shall determine the percentage yield of Ag. This can be obtained as follow:

Actual yield = 20 g

Theoretical yield = 32.4 g

Percentage yield =?

Percentage yield = Actual yield /Theoretical yield × 100

Percentage yield = 20 / 32.4 × 100

Percentage yield = 61.7%

6 0

3 years ago

A helium balloon contains 0.46g off helium. how many moles of helium does it contain?

EastWind [94]

(0.48 gram) x (1mole / 4.0 gram) = 0.48/4.0 = 0.12 mole

3 0

3 years ago

Which of the following reactions have a positive ΔSrxn? Check all that apply.

PolarNik [594]

Answer:

The reactions that have a <em>positive ΔS rxn </em>are the first and the fourth choices:

<em>2A(g) + B(s) → 3C(g)</em>

<em>2A(g) + 2B(g) → 5C(g)</em>

Explanation:

<em>ΔS rxn </em>is the change of entropy of the chemical reaction.

ΔS rxn = S after reaction - S before reaction.

Therefore, a positive ΔS rxn means that the entropy after the reaction is greater than the entropy before the reaction.

You may use some assumptions to predict whether a reaction will lead an increase or decrease of the entropy.

First, assume that all the non-shown conditions, such as temperature and pressure, are constant.

Under that assumption, and from the meaning of entropy as a measure of the disorder or randomness of a system you can predict the sign of the change of entropy.

<em><u>2A(g) + B(s) → 3C(g)</u></em>

1) The solid compounds, B(s) in this case, are very ordered and so they have low entropy.

2) Gas molecules are highly disordered (scattered), and the greater the number of molecules of the gas the larger the entropy, S).

Hence, since the product side shows 3 gas molecules and the reactant side shows 2 gas molecules and 1 solid molecule, you predict that the products have a larger entropy than the reactants, meaning an increase in entropy: <em>ΔS rxn is positive.</em>

<em><u>2A(g) + B(g) → C(g)</u></em>

Using the same reasoning, 3 gas molecules in the reactant side have more entropy than 1 molecule in the product side, and so the reaction leads to a decrease in the entropy: ΔS rxn is negative

<u><em>A(g) + B(g) → C(g)</em></u>

Again, 2 gas molecules in the reactant side have more entropy than 1 molecule in the product side, and so the reaction leads to a decrease in the entropy: ΔS rxn is negative

<u><em>2A(g) + 2B(g) → 5C(g)</em></u>

With the same reasoing, 5 molecules in the product side, lets you predict that will have more entropy than 4 molecules in the reactant side, and, the entropy will increase: <em>ΔS rxn is positive.</em>

6 0

4 years ago

Which separation techniques will you apply for the separation of the following? a) oil from water b) kerosene and petrol c) salt

REY [17]

Answer:

A) Separating funnel method

B) Simple Distillation

C) Evaporation

D) Sublimation

E) It is based on the principle of separation whereby even though two substances are dissolved in the same solvent, their respective solubilities could be different. Thus, the component that has more solubility will rise fastest and will therefore get separated from the mixture.

Explanation:

A)

B) Kerosene and petrol are both miscible liquids and the difference in their boiling point temperature is not more than 25°C. Thus, we make use of Simple distillation.

C) Can be separated by evaporation where the water is boiled and it evaporates and leaves the salt behind

D) To separate camphor from salt, we use sublimation so the camphor can change directly from solid to the gas state without passing through the liquid state.

E) Chromatography is used to separate components of a mixture.

It is based on the principle of separation whereby even though two substances are dissolved in the same solvent, their respective solubilities could be different. Thus, the component that has more solubility will rise fastest and will therefore get separated from the mixture.

7 0

3 years ago