Question 9(Multiple Choice Worth 4 points)
(08.01 LC)

What happens to water when it warms above 4 °C?

It contracts.
It forms ice.
Its density decreases.
Its composition changes.

Answer:The second law

Answer:

second

Explanation:

Answer:

[tex]p = \boxed{\text{593 torr}}[/tex]

Explanation:

For this question, we must use Dalton's Law of Partial Pressures:

The partial pressure of a gas in a mixture of gases equals its mole fraction times the total pressure:

[tex]p = \chi p_{\text{tot}}[/tex]

Data:

χ = 0.7808

[tex]p_{\text{tot}} = \text{ 760 torr}[/tex]

Calculation:

[tex]p = 0.7808 \times \text{ 760 torr}\\\\p= \boxed{\textbf{593 torr}}[/tex]

The partial pressure of nitrogen in the air, when the atmospheric pressure is 760 torr, is 593.4 torr. This is calculated using the given formula and the mole fraction of nitrogen.

The mole fraction of nitrogen (N₂) in the air is 0.7808 or 78.08%. This means that 78.08% of the molecules in the air are nitrogen. When talking about the partial pressure of gases, it means the contribution of that gas to the total pressure of the mixture. The partial pressure of any gas can be calculated using the formula P = (Patm) X (percent content in mixture). In this case, the atmospheric pressure (Patm) is 760 mm Hg, or torr. To find the partial pressure of nitrogen (N₂), multiply the atmospheric pressure by the mole fraction of nitrogen. So, Pₙ₂ = (760 torr) X (0.7808) = 593.4 torr. Therefore, when the atmospheric pressure is 760 torr, the partial pressure of nitrogen in the air is 593.4 torr.

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Answer:

The wood

Explanation:

The block of wood shall float in the water while the iron key would sink due to the weight.

The iron key is easier to find in the bathtub as it will sink due to its density, while the wood floats. This behavior is explained by Archimedes' principle concerning buoyant force and the displacement of water.

Between the iron key and the piece of wood, the iron key would be easier to find because it would sink to the bottom of the bathtub due to its higher density compared to water. Objects denser than water, such as iron, will not float and instead displace a volume of water equal to their own volume as they sink. This concept is explained by Archimedes' principle, which states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. Since iron is much denser than water, it displaces a small volume of water before reaching the bottom of the tub. On the other hand, wood is less dense than water and therefore floats on the surface. This is because the wood displaces a volume of water equal to its weight before it is completely submerged, allowing it to float.

In the bathtub experiment mentioned in the question, marbles were dropped into a partially filled bathtub sink to the bottom. While part of their weight is supported by the buoyant force, the downward force on the bottom of the tub increases by exactly the weight of the marbles because the water displaced by the marbles has to go somewhere, exerting an equal force downward.

Answer:

as the world is changing we change also

Explanation:

We must always check and recheck are a hypothesis

Answer:

Explanation:

Because sometimes in the details of an experiment there are details hidden away that no one has thought to exploit.

I like to use Cancer as an example. Most cancers have drugs associated with them that are actually poisons (although  scientists are getting much, much better in reducing side effects).

But the main purpose until recently is an example of survival of the fittest. Think Darwin.  The drug kills off the cancer cells that are most easily killed off. That leaves the slower growing more deadly forms of the cancer behind and they finish the job, because there is nothing to control them, nor is anything competing with them.

Without finding this out, biologists would be at a loss of where to turn. Oncologists repeat the same treatment hundreds of times until the have a feel for how the cancer works. Then they are better equipped to tackle the problem a new.

Answer:

The acid dissociation constant, _Ka__, is a quantitative measure of acid strength

Explanation:

Given that the product is slippery and turns litmus paper blue. It probably contains a base (Option B)

A base is a substance which dissolves in water to produce hydroxide ion, OH¯

A base has been known to neutralize, producing salt and water.

However, a base can easily be tested for by using litmus paper.

A solution of base will turn red litmus paper blue.

With the above information about base, we can conclude that the product described in the question given above contains a base (option B)

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Answer:

D) hydrochloric acid.

Explanation:

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g),

It is clear that 1.0 moles of Zn react with 2.0 moles of HCl to produce 1.0 moles of ZnCl₂ and 1.0 mole of H₂.

∴ 2.0 mol of Zn (the remaining 2.0 mol is in excess) react completely with 4.0 mol of HCl with (1: 2) molar ratio.

So,

the limiting reactant is HCl and the excess reactant is Zn.

Thus, the right choice is: D) hydrochloric acid.

Final answer:

Explanation on how to determine the limiting reactant in a chemical reaction involving zinc and hydrochloric acid.

Explanation:

The limiting reactant in a chemical reaction is the reactant that gets consumed completely first, limiting the amount of product formed. To determine the limiting reactant, we compare the moles of each reactant to the stoichiometry of the balanced equation.

In the reaction Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g), if you have 4 moles of zinc and 4 moles of hydrochloric acid, you need to use stoichiometry to see which reactant will be completely consumed first.

Based on the balanced equation, the limiting reactant between zinc and hydrochloric acid is hydrochloric acid as only 2 moles of HCl are needed to react completely with 1 mole of zinc.

Answer:

A. Population sizes are limited by the amount of resources that are available.

Explanation:

Think about it, the more people you have, the more food & water you need.

SO the answer is A.

(prove me wrong)

Answer:

77.98 g/mol ≅ 78.0 g/mol.

Explanation:

Molar mass of Al(OH)₃ = (Atomic mass of Al) + 3(Atomic mass of O) + 3(Atomic mass of H)

Atomic mass of Al = 26.98 g/mol. & Atomic mass of O = 16.0 g/mol & Atomic mass of H = 1.0 g/mol.

∴ Molar mass of Al(OH)₃ = (26.98 g/mol) + 3(16.0 g/mol) + 3(1.0 g/mol) = 77.98 g/mol ≅ 78.0 g/mol.

Final answer:

To find the molar mass of Al(OH)3, calculate the total mass of one mole by adding the molar mass of each element: Al, O, and H. The molar mass of Al(OH)3 is approximately 77.0 g/mol.

Explanation:

To find the molar mass of Al(OH)3, we need to calculate the total mass of one mole of Al(OH)3.

First, we calculate the molar mass of each element in Al(OH)3:

Al: 1 mole * 26.98 g/mole = 26.98 g/mole

O: 3 moles * 16.00 g/mole = 48.00 g/mole

H: 3 moles * 1.01 g/mole = 3.03 g/mole

Adding up the masses of each element gives us a total molar mass of Al(OH)3:

26.98 g/mole + 48.00 g/mole + 3.03 g/mole = 77.01 g/mole

Therefore, the molar mass of Al(OH)3 is approximately 77.0 g/mol to the nearest 0.1 g/mol.

Answer:

C) nitrogen monoxide

Explanation:

Answer:

c

Explanation:

Bubbling And Fizzing

Answer:

Signs of chemical reactions are, if gas or bubbles are present, if a color changes occurs, or if a precipitate is formed, that could indicate that a chemical reaction has occurred.

Explanation:

Answer:

I attached the answer as an image. I also drew in the two most acidic hydrogens.

Explanation:

This goes through the 'benzyne' intermediate, meaning it does an E2-looking reaction by expelling a leaving group (chloride) from the adjacent part of the ring using the amide as a strong base. The triple-bonded benzyne has absurd bond angle strain, and is vulnerable to a good nucleophile like an amide ion, and the resultant sp2 anion is then reprotonated by the acid. I didn't draw in the acid-base reaction in step one, or the spectator ion (sodium).

The both major organic products are 3-amino-2-methyltoluene and 4-amino-2-methyltoluene.

The reaction of 4-chloro-2-methyltoluene with sodium amide is an E2 reaction. The abstraction of hydrogen ion by a base and the loss of chloride ion occurs simultaneously leading to the formation of a benzyne intermediate.

This benzyne intermediate is attacked by the amide ion and H3O+ to yield the products; 3-amino-2-methyltoluene and 4-amino-2-methyltoluene. The  detailed mechanism of the reaction is shown in the images attached below.

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Answer:

The correct option is D.

Explanation:

Radioactive substances usually emit different types of particles when they are decaying. Such particles include alpha particles, beta particles and gamma ray. When an alpha particle is emitted from an unstable radioactive nucleus such nucleus usually lost an atomic mass that correspond to that of helium atom. Note that an alpha particle is made up of two protons and two neutrons, which result in mass number of 4. Thus, a nucleus that emit an alpha particle will have its mass number (atomic mass) reduce by 4 and atomic number that is reduced by 2.  

Answer:C

Explanation:

The equation which best describes the reaction between Ni(OH)₂ & HCl is Ni(OH)₂(s) + 2HCl(l) → NiCl₂(aq) + 2H₂O(l).

Those reaction in which acids combine with bases to form water molecule and salt is known as neutralization reaction.

In the given question, nickel hydroxide Ni(OH)₂ is a base and when it reacts with hydrochloric acid it will form water molecule and nickel chloride salt, and chemical reaction for this changes will be represent as follow:

Ni(OH)₂(s) + 2HCl(l) → NiCl₂(aq) + 2H₂O(l)

Reactions except this equation is not correct as in that equations formation of desired products will not takes place.

Hence Ni(OH)₂(s)+2HCl(l)→NiCl₂(aq)+2H₂O(l) best describes the change.

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Answer:

33 degrees

Explanation:

The critical angle for a light ray moving from a denser medium with refractive index [tex]n_1[/tex] to a second medium with refractive index [tex]n_2[/tex] is given by

[tex]\theta_c = sin^{-1} (\frac{n_2}{n_1})[/tex]

In this case, the critical angle occurs when light moves from diamond to water. The index of refraction of the two materials are:

[tex]n_d = 2.42[/tex] for diamond

[tex]n_w = 1.33[/tex] for water

So the critical angle is

[tex]\theta_c = sin^{-1} (\frac{1.33}{2.42})=sin^{-1}(0.550)=33.3^{\circ}[/tex]

Answer:

Synthesis

Explanation:

Answer: Single replacement

[tex]Fe+CuSO_4\rightarrow Cu+FeSO_4[/tex]

Explanation:

Single replacement reaction is a chemical reaction in which more reactive element displaces the less reactive element from its salt solution.

Iron being more reactive than copper would displace copper from its salt solution and thus will generate copper and iron sulphate.

The chemical equation representing iron metal plus copper (II) sulfate solution yields iron (II) sulfate solution and copper metal is:

[tex]Fe+CuSO_4\rightarrow Cu+FeSO_4[/tex]

I think the answer would be True

Answer:

C) 4.8 L NH₃.

Explanation:

N₂(g) + 3H₂(g) → 2NH₃(g),

It is clear that 1.0 moles of N₂ react with 3.0 moles of H₂ to produce 2.0 moles of NH₃.

It is known that at STP: every 1.0 mol of any gas occupies 22.4 L.

1.0 mol of N₂ represents → 22.4 L.

??? mol of N₂ represents → 2.4 L.

∴ 2.4 L of N₂ represents = (1.0 mol)(2.4 L)/(22.4 L) = 0.1071 mol.

1.0 mol of N₂ produce → 2.0 mol of NH₃, from stichiometry.

0.1071 mol of N₂ produce → ??? mol of NH₃.

∴ The no. of moles of NH₃ = (2.0 mol)(0.1071 mol)/(1.0 mol) = 0.2142 mol.

1.0 mol of NH₃ represents → 22.4 L, at STP.

0.2142 mol of NH₃ represents → ??? L.

∴ The no. of liters of NH₃ will be produced = (0.2142 mol)(22.4 L)/(1.0 mol) = 4.789 L ≅ 4.8 L.

So, the right choice is: C) 4.8 L NH₃.

Final answer:

Using Avogadro's law and the stoichiometry of the chemical equation for the production of ammonia, 2.4L of nitrogen gas will produce 4.8L of ammonia gas at standard temperature and pressure (STP).

Explanation:

According to Avogadro's law, equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. Therefore, we can use the balanced chemical equation N2(g) + 3 H2(g) → 2 NH3(g) to determine the volume of ammonia produced by the reaction. The equation tells us that one volume of nitrogen reacts with three volumes of hydrogen to produce two volumes of ammonia. Since we are assuming standard temperature and pressure (STP), we can directly relate the volumes of gases involved in the reaction.

If 2.4L of N2 are reacted with an excess of hydrogen, according to the stoichiometry of the reaction, it would produce twice the volume of NH3 because for every one volume of N2, two volumes of NH3 are produced. Therefore, 2.4L of N2 would produce 4.8L of NH3. Accordingly, the correct answer is C) 4.8L NH3.

Answer:

Here you go buddy. Good Luck

Explanation:

Chemical formula of a compound tells us about the number of atoms of elements that are present in a compound.

For the given options:

1. Nitric acid

This is an acid in which one hydrogen, 1 nitrogen and 3 oxygen atoms are present. The chemical formula for this compound is [tex]HNO_3[/tex]

2. Sulfurous acid

This is an acid in which two hydrogen, 1 sulfur and 3 oxygen atoms are present. The chemical formula for this compound is [tex]H_2SO_3[/tex]

3. Hypochlorous acid

This is an acid in which one hydrogen, 1 chlorine and 1 oxygen atoms are present. The chemical formula for this compound is [tex]HClO[/tex]

4. Ammonia

This is an acid in which three hydrogen and 1 nitrogen atoms are present. The chemical formula for this compound is [tex]NH_3[/tex]

5. Sulfuric acid

This is an acid in which one hydrogen, 1 sulfur and 4 oxygen atoms are present. The chemical formula for this compound is [tex]H_2SO_4[/tex]

Answer:

A

Explanation:

One of the main complaints about hydropower is that it will change the ecosystem. You can read about the history of any dam and you will find that most of them have involved evacuation. That means that farmland was lost and replaced by a lake behind the dam. The energy comes from water cascading over the top of the dam to its bottom.

It does not produce radiation.

It does not burn fossil fuels. It's clean and does not pollute the air.

So there are no greenhouse gases involoved.

Answer:

change the ecosystem

Explanation:

Equilibrium shifts to produce more reactant.

Answer:

Explanation:

A hydrocarbon with a double bond in its carbon skeleton is an alkene and has the general form:

This is, the number of hydrogen atoms is twice the number of carbon atoms.

On the other hand, alkanes have only single bonds, and the compounds with a triple bond in its carbon skeleton are alkynes.

Review each choice:

1) C₃H₈:

2) C₂H₆

3) CH₄

4) C₂H₄

So, this is the correct answer.

5) C₂H₂

Answer:

[tex]\boxed{\text{[PCl$_{5}$] = 0.0077 mol/L; [PCl$_{3}$] = [Cl$_{2}$] = 0.117 mol/L}}[/tex]

Explanation:

The balanced equation is

PCl₅(g) ⇌ PCl₃(g) + Cl₂(g)

You don't give the volume of the flask, so I assume it is 1 L.

We can set up an ICE table to organize our calculations.

[tex]\begin{array}{lccccc} & \text{PCl}_{5} & \rightleftharpoons & \text{PCl}_{3} & + & \text{Cl}_{2} \\\text{I/mol}\cdot\text{L}^{-1}: & 0.125 & & 0 & & 0 &\\\text{C/mol}\cdot\text{L}^{-1}: & -x & & +x & & +x &\\\text{E/mol}\cdot\text{L}^{-1}:& 0.125-x & & x & & x &\\\end{array}[/tex]

[tex]K_{\text{c}} = \dfrac{\text{[PCl$_3$][Cl$_2$]}}{\text{[PCl$_5$]}} = \dfrac{x^{2}}{0.125-x} = 1.80[/tex]

Check for negligibility

[tex]\dfrac{0.125}{1.80} = 0.0674 < 400.[/tex]

x is not negligible, so we must solve a quadratic.

[tex]x^{2} = 1.80(0.125 - x)\\x^{2} = 0.225 - 1.80x\\x^{2} + 1.80x - 0.225 = 0\\[/tex]

Solve for x.

x = 0.1173

[PCl₅] = 0.125 - x = 0.125 – 0.1173 = 0.0077 mol·L⁻¹

[PCl₃] = x = 0.117 mol·L⁻¹

 [Cl₂] = x = 0.117 mol·L⁻¹

[tex]\boxed{\textbf{[PCl$_{5}$] = 0.0077 mol/L; [PCl$_{3}$] = [Cl$_{2}$] = 0.117 mol/L}}[/tex]

Check:

[tex]\dfrac{0.117^{2}}{0.0077} = 1.80\\\\\dfrac{0.0138}{0.0077} = 1.79[/tex]

Close enough. It checks.

In a chemical reaction when the reactants split to form two or more products are called a decomposition reaction. It is generally a breakdown of the reactants to yield products.

The concentrations of [tex]\rm PCl_{5}[/tex]  is 0.0077 mol/L, [tex]\rm PCl_{3}[/tex] and [tex]\rm Cl_{2}[/tex]  is 0.177 mol/L.

The balanced equation given is:

[tex]\rm PCl_{5} (g) \rightleftharpoons \rm PCl_{3} (g) + Cl_{2} (g)[/tex]

See the ICE table for the equation in the attached image below.

According to the table:

[tex]Kc = \dfrac{[\rm PCl_{3}] [Cl_{2}]}{[\rm PCl_{5}]}[/tex]

[tex]1.80 =\dfrac { x^{2} }{0.125 - x}[/tex]

Check the value for the negligibility:

[tex]\dfrac{0.125 }{1.80} = 0.0674 < 400[/tex]

From above it can be stated that it is not negligible and will be solved by the quadratic equation:

[tex]\begin{aligned}x^{2} &= 1.80 (0.125 - x)\\\\x^{2} &= 0.225 - 1.80x\\\\0 &= x^{2} + 1.80 x - 0.225\end{aligned}[/tex]

Solving further for x:

x = 0.1173

For gases:

[tex]\begin{aligned} \rm [PCl_{5}] &= 0.125 - x \\\\\rm [PCl_{5}] &= 0.125 - 0.1173 \\\\&= 0.0077 \;\rm mol L^{-1}\end{aligned}[/tex]

And,

[tex]\begin{aligned} \rm [PCl_{3}] &= 0.117 \;\rm mol L^{-1}\\\\\rm [Cl_{2}] &= 0.117 \;\rm mol L^{-1} \end{aligned}[/tex]

Therefore, the concentration of each gases are [tex]\rm PCl_{5}[/tex] is 0.0077 mol/L, [tex]\rm PCl_{3}[/tex] and [tex]\rm Cl_{2}[/tex] is 0.177 mol/L.

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Answer:

- 228.6 kJ/mol.

Explanation:

∵ ΔGrxn = ∑ΔGf, products - ∑ΔGf, reactants

4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O,  

∴ ΔGrxn = [6(ΔGf, H₂O) + 4(ΔGf, NO)] - [4(ΔGf, NH₃) + 5(ΔGf, O₂)]

ΔGrxn = – 957.9 kJ, ΔGf, H₂O = ??? KJ/mol, ΔGf, NO = 86.71 kJ/mol, ΔGf, NH₃ = - 16.66 kJ/mol, ΔGf, O₂ = 0.0 kJ/mol.

∴ – 957.9 kJ = [6(ΔGf, H₂O) + 4(86.71 kJ/mol)] - [4(- 16.66 kJ/mol) + 5(0.0 kJ/mol)].

– 957.9 kJ = 6(ΔGf, H₂O) + 346.8 kJ/mol + 66.64 kJ/mol

– 957.9 kJ = 6(ΔGf, H₂O) + 413.8 kJ/mol

6(ΔGf, H₂O) = – 957.9 kJ - 413.8 kJ/mol = - 1372 kJ/mol.

∴ ΔGf, H₂O = (- 1372 kJ/mol)/6 = - 228.6 kJ/mol.

The element initially has an atomic number of 88 and it decays to an atomic number of 82. This is achieved by the emission of three alpha particles in a process known as radioactive decay. No beta particles are emitted in this case.

In your question, an element of atomic number 88 decays to an element of atomic number 82. This radioactive decay is a form of alpha decay. In alpha decay, the atomic number decreases by two and the mass number decreases by four, as one alpha particle (consisting of two neutrons and two protons) is emitted from the nucleus.

Therefore, in order to move from an atomic number of 88 to 82, three alpha particles must be emitted. The emission of any beta particles (which transform a neutron into a proton) would have the effect of increasing the atomic number, which is not what happens in this case.

Hence, the correct answer is three alpha particles.

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The density of NO2 in a 4.50 L tank at 760.0 torr and 25.0 °C is approximately 1.64 g/L.

To calculate the density of NO2 in a 4.50 L tank at 760.0 torr and 25.0 °C, we can use the ideal gas law and the molar mass of NO2. The ideal gas law equation is PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature. Rearranging the equation, we have n = PV/RT. First, we need to calculate the number of moles of NO2 in the tank. We can calculate this by dividing the pressure in torr by the ideal gas constant (0.08206 L atm/K mol), multiplied by the temperature in Kelvin. Then we can divide the calculated number of moles by the volume of the tank to get the molar concentration. Finally, we can divide the mass of NO2 by the volume of the tank to get the density. Using this method, the density of NO2 in the 4.50 L tank at 760.0 torr and 25.0 °C is approximately 1.64 g/L (Option A).

Answer:

0.07172 L = 7.172 mL.

Explanation:

where, P is the pressure of the gas in atm (P = 1.0 atm, Standard P).

V is the volume of the gas in L (V = ??? L).

n is the no. of moles of the gas in mol (n = 3.2 x 10⁻³ mol).

R is the general gas constant (R = 0.0821 L.atm/mol.K),

T is the temperature of the gas in K (T = 273 K, Standard T).

∴ V = nRT/P = (3.2 x 10⁻³ mol)(0.0821 L.atm/mol.K)(273 K)/(1.0 atm) = 0.07172 L = 7.172 mL.

To calculate the volume of 3.2 x 10^-3 mol CO2 at STP, we can use Avogadro's Law. The volume can be calculated by multiplying the number of moles by the molar volume of a gas at STP, which is 22.4 liters/mol.

To calculate the volume of gas at STP (Standard Temperature and Pressure), we can use Avogadro's Law. Avogadro's Law states that equal volumes of gases, at the same temperature and pressure, contain the same number of particles (moles).

First, we need to convert the given number of moles of CO2, which is 3.2 x 10^-3 mol, into liters by using the molar volume of a gas at STP, which is 22.4 liters/mol. Multiplying the number of moles by the molar volume gives us the volume:

Volume = 3.2 x 10^-3 mol * 22.4 L/mol = 0.07168 L

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Answer:

16.0%.

Explanation:

Volume percent of a substance is the ratio of the substance volume to the solution volume multiplied by 100.

V % of ethanol = (volume of ethanol / volume of the solution) x 100.

volume of ethanol = 90.0 mL, volume of the solution = 550.0 mL.

∴ V % of ethanol = (90.0 mL / 550.0 mL) x 100 = 16.36% ≅ 16.0%.