How many moles of NH4NO3(s) must be dissolved in water so that 73.0 kJ of heat is absorbed from the water? (The molar heat of solution of NH4NO3 is 25.7 kJ/mol.)

The empirical formula of the compound is LiBr.

To determine the empirical formula of the compound, we need to find the ratio of the number of moles of each element in the compound.

First, let's find the number of moles for each element:

Lithium (Li):

Mass of lithium (given) = 16 g

Relative atomic mass of lithium (from the periodic table) = 7

Number of moles of lithium = Mass / Relative atomic mass = 16 g / 7 g/mol ≈ 2.29 moles

Bromine (Br):

Mass of bromine (given) = 183 g

Relative atomic mass of bromine (from the periodic table) = 80

Number of moles of bromine = Mass / Relative atomic mass = 183 g / 80 g/mol ≈ 2.29 moles

Now, we need to find the simplest whole-number ratio of moles of lithium to moles of bromine. Both elements have approximately 2.29 moles. To find the ratio, we can divide both moles by the smallest number of moles:

Number of moles of Li = 2.29 moles / 2.29 moles = 1

Number of moles of Br = 2.29 moles / 2.29 moles = 1

The empirical formula of the compound is LiBr, indicating that there is one lithium atom for every one bromine atom in the compound.

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To find the empirical formula of a compound containing lithium and bromine, calculate the moles of each element based on their given masses and the relative atomic masses, then express the mole ratio in simplest whole number terms to obtain the empirical formula.

The empirical formula of a compound can be found by dividing the mass of each element by its atomic mass to find the number of moles of each element and then expressing those values in the simplest whole number ratio. To determine the empirical formula for the compound containing lithium and bromine, we do the following steps:

Once we have the simplest whole number ratio of the moles of lithium to moles of bromine, that ratio will be used to write the empirical formula.

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Answer : The molar mass of a gas is, 48.3 g/mole

Solution : Given,

Molar mass of argon gas = 40 g/mole

According to the Graham's law, the rate of effusion of gas is inversely proportional to the square root of the molar mass of gas.

[tex]R\propto \sqrt{\frac{1}{M}}[/tex]

or,

[tex]\frac{R_1}{R_2}=\sqrt{\frac{M_2}{M_1}}[/tex]

where,

[tex]R_1[/tex] = rate of effusion of a gas

[tex]R_2[/tex] = rate of effusion of argon gas

[tex]M_1[/tex] = molar mass of a gas

[tex]M_2[/tex] = molar mass of argon gas

As per question,

[tex]R_1=0.91\times R_2[/tex]

Now put all the given values in the above formula, we get the molar mass of a gas.

[tex]\frac{0.91\times R_2}{R_2}=\sqrt{\frac{40g/mole}{M_1}}[/tex]

[tex]M_1=48.30g/mole[/tex]

Therefore, the molar mass of a gas is, 48.3 g/mole

Answer:

CaCl2

Explanation:

Calcium: Ca

Chloride or chlorine: Cl

Chloride: it is name of chlorine when it has a ion

calcium has a charge of +2 and  Chlorine has a charge of -1

this is a ionic bond, so the charges of the two atoms have to equal or cancel out, so u need two  Chlorine

and then it will be calcium +2 and chloride -2

2-2=0, they are neutral and we are right

CaCl2

Answer: [tex]3.13\times 10^{23}molecules[/tex]

Explanation: To calculate the moles, we use the formula:

[tex]Moles=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{9.34g}{18g/mol}=0.52mol[/tex]  

1 mole of water contains=[tex]6.023\times 10^{23}molecules[/tex] of water

0.52 moles of water contain=[tex]\frac{6.023\times 10^{23}}{1}\times 0.52=3.13\times 10^{23}molecules[/tex] of water

One or more than one atoms bonds and makes up the molecules, it can be the same or different atoms that make up the compounds. Molecules present in the 9.34 gm of water are [tex]\rm 3.13 \times 10^{23}[/tex].

Given,

Mass of the water (m) = 9.34 gm

The molar mass of the water (M)= 18 g/mol

From the mass and the molar mass number of the moles can be estimated:

[tex]\rm Moles (n) = \dfrac{\;\rm Mass}{\rm Molar \;mass}[/tex]

Substituting values in the above formula:

[tex]\begin{aligned}\rm n &= \dfrac{9.34\;\rm g}{18\;\rm g/mol}\\\\&= 0.52\;\rm mol\end{aligned}[/tex]

We know that,

1 mole of water = [tex]\rm 6.023 \times 10^{23}[/tex] molecules of water

0.52 moles of water = X molecules

Solving for X:

[tex]\begin{aligned} \rm X &= 0.52 \times \rm 6.023 \times 10^{23}\\\\&= \rm 3.13 \times 10^{23}\end{aligned}[/tex]

Therefore, [tex]\rm 3.13 \times 10^{23}[/tex] molecules are present.

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Answer;

Explanation:

When iron reacts with the moisture present in air then an oxide layer tends to develop on the surface of iron. This process is known as rusting of iron.

Chemical formula of rust is [tex]Fe_{2}O_{3}.xH_{2}O[/tex]. This layer of oxide on the surface of iron is orange-brown in color.

This change is a chemical change as a new compound iron oxide has formed in this process of rusting.

Hence, this orange-brown color on the surface of iron helps us to know that rusting has taken place.

Answer: 111 g

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

To calculate the moles, we use the equation:

[tex]\text{Number of moles of calcium}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{40g}{40g/mol}=1mole[/tex]

[tex]\text{Number of moles of chlorine}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{71g}{71g/mol}=1mole[/tex]

[tex]Ca+Cl_2\rightarrow CaCl_2[/tex]

1 moles of calcium react with 1 mole of chlorine to give 1 mole of calcium chloride.

Mass of calcium chloride =[tex]moles\times {\text {molar mass}}=1mol\times 111g/mol=111g[/tex]

Thus 111 g of calcium chloride is produced.

its actually answer 2

The oxidation number is defined as the total number of electrons gained or lost in a chemical bond with another atom.

The oxidation number of the given elements are:

1. CaF₂ or calcium fluoride is an ionic bond. The oxidation number of Calcium is +2 and that of Flourine is -1. The net charge on the compound is zero.

2. Sulfuric acid is a type of covalent bond. The oxidation number of Hydrogen is +1, Sulfur is +6, and that of Oxygen is -2. The net charge on the compound is zero.

3. Calcium sulfate is a type of covalent bond and ionic bond. The oxidation number of Calcium is +2, Sulfur is +6, and that of Oxygen is -8. The net charge on the compound is zero.

4. Hydrogen Flouride is a type of covalent bond. The oxidation number of Hydrogen is +1 and that of Flourine is -1. The net charge on the compound is zero.

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Answer:

All the above

Explanation:

Answer:

Heat has shorter wavelengths than visible light.

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The balanced chemical equation has been [tex]\rm 3\;CaCO_3\;\rightarrow\;3\;CaO\;+\;3\;CO_2[/tex].

The balanced equation can be given to follow the law of conservation of mass. with equal  number of atoms of each elements has been present on the product and the reactant side.

The given equation has been written with addition of 3 as a coefficient to the carbon dioxide has been:

[tex]\rm CaCO_3\;\rightarrow\;CaO\;+\;3\;CO_2[/tex]

The number of elements of oxygen on product side has been 6 atoms for carbon dioxide and 1 oxygen atom for calcium oxide. The total oxygen on product side has been 7. The reactant has the presence of 3 oxygen atoms.

The reaction has been balanced with equal atoms on both the sides as:

[tex]\rm 3\;CaCO_3\;\rightarrow\;3\;CaO\;+\;3\;CO_2[/tex]

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Answer;

Ge and As.

Explanation;

Elements Ge and As belong in the same period as krypton.

Each row of the periodic table is called the period.

Elements in each period have the same number of electron shells.

These elements in the same period do not have similar properties- the properties change greatly across every period. Krypton is in period four therefore all the elements in period 4 have four electrons shells.

In order to practice sustainable agriculture, less external energy must be used, and renewable energy sources must take their place. To feed a growing world without damaging the ecosystem is the goal of sustainable agriculture. The correct option is C.

Crop rotation, the process of rotating various crops in the same area, helps maintain the soil's health and productivity by creating a mix of nutrients. This may lessen the need for pesticides and fertilizers to kill weeds and insects.

Agriculture that is sustainable generates a lot of food without consuming too many resources or harming the environment. Agriculture develops self-sustaining agricultural and livestock-raising systems that are, like nature, based on natural principles.

Thus the correct option is C.

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The true statement about the periodic table is that metals are found on the left side of the periodic table, and nonmetals are located on the upper right, with a diagonal band of semimetals separating them.

The correct answer to the question "Which sentence about the periodic table of elements is true?" is that metals are found on the left side of the periodic table. This is because the elements can be categorized generally into metals, nonmetals, and semimetals, and it is known that metals occupy the left side of the periodic table. Nonmetals are found primarily on the upper right side, and they are divided from metals by a diagonal band of semimetals. Specifically, Group 1 contains the alkali metals, and Group 2 houses the alkaline earth metals, while Group 17 has the halogens and Group 18 has the noble gases, which are nonmetals.

The correct answer is B. The carrying capacity will decrease and the owl population will decrease.

Explanation:

In ecology, the carrying capacity refers to the number of organisms an ecosystem or area can sustain because it provides water, shelter, food, etc. This carrying capacity decreases due to the destruction of habitat or natural disasters that reduces the resources or habitable area.

This implies, in the case presented, the carrying capacity of the forest will decrease because the resources on in for owls are reduced to half due to housing development. Besides this, it is expected the owl population decreases because with less food, water, and other resources such as trees to nest ess owls will survive and reproduce. Thus, in this case, "the carrying capacity will decrease and the owl population will decrease".

Final answer:

The correct answer is "- delta G". For a spontaneous reaction, delta G must always be negative. This indicates that the reaction releases free energy and can proceed without external intervention.

Explanation:

The correct answer for which change will always be true for a spontaneous reaction is - delta G. This is because a spontaneous reaction is defined as one that proceeds on its own without any external influence, and for such a reaction, the change in Gibbs free energy, represented as delta G, must always be negative. This negative delta G indicates that the process is releasing free energy. The Gibbs free energy equation delta G = delta H - T delta S tells us that the spontaneity of a reaction depends on both the enthalpy change (delta H) and the entropy change (delta S) along with the absolute temperature in Kelvin (T). If the enthalpy change is negative (- delta H) and the entropy change is positive (+ delta S), delta G will always be negative, indicating a spontaneous reaction at all temperatures. However, if delta H is positive and delta S is negative, the reaction will never be spontaneous as delta G will be positive.

Answer : Option B) Air

Explanation : As the speed of light depends on the refractive index of the medium; then according to Snell's law (refer the attachment) Air is the medium that would have the longest wavelength amongst the given options.

As the refractive indexes of water is 1.33, glass is 1.5 and diamond 2.42 are much higher than air. Therefore, it will be the medium which will allow maximum light to pass through it easily and hence, will be the medium with longest wavelength.

The correct answer is air.  

The refractive indexes of air, water, glass and diamond are1.0003, 1.33, 1.5 and 2.42 respectively. The refractive index of air is the lowest so it is the medium through which light will travel faster with the longest wavelength. The higher the refractive index the denser the medium and the slower is the speed with which light will travel through this medium.  

The equilibrium concentration of cl2 at 227C is mathematically given as

[Cl2] = 2.4X10^-4 m

Question Parameters:

If a reaction mixture initially contains 0.195 m so2cl2

concentration of cl2 at 227

Generally the equation for the Chemical Reaction  is mathematically given as

SOCl2 ⇄ SO2 +Cl2

Therefore

[tex]K=\frac{ [SO2][Cl2]}{SOCl2}[/tex]

2.99X10^-7 = (X)(X)/(0.195-X)

X = 0.00024 = 2.4 X10^-4

[Cl2] = 2.4X10^-4 m

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An incandescent bulb becomes hotter than a fluorescent bulb when turned on because in a regular incandescent bulb, there is tungsten wire where electricity is converts into heat. A regular incandescent light bulb requires 4 times more energy than a fluorescent bulb in order to produce the same amount of light. The conversion is such that for a 75-watt bulb, temperature get raised to approximately 2000 K. For such a high temperature, the radiating energy from the wire have some visible light. In such bulbs, 90% of the electricity get consumed in producing heat and only 10% produces light thus, they are not much efficient source of light.

On the other hand, fluorescent bulbs produce light with less amount of heat. In them, 40% of electricity is consumed in producing light and 60% in heat which is very less as compared to heat produced by a incandescent bulb. This is because when it get turned on, mercury atoms inside the bulb collides with electrons and produce UV light  which is then converted into visible light using thin layer of phosphor power present inside the bulb. This produces low amount of heat thus, the bulb stays cooler, the bigger size of bulb also helps in dispersing heat.

Therefore, a fluorescent light bulb is not as hot as an incandescent light bulb.

Particles in plasmas collide more often, but that does not necessarily give them higher temperature.

Plasma particles have high kinetic energy (they move quickly).

Plasma particles are far apart.

The plasma in a fluorescent bulb has a low density.

The concentration of [H2SO4] is obtained from; [NaOH] × VNaOH/ 2× VH2SO4

The equation of the reaction is;

2NaOH(aq) + H2SO4(aq) ------>  Na2SO4(aq) + 2H2O(l)

Number of moles of H2SO4(nH2SO4) = [H2SO4] × VH2SO4

Number of moles of NaOH(nNaOH) = [NaOH] × VNaOH

Where;

[H2SO4] = concentration of H2SO4

VH2SO4 = volume of H2SO4

[NaOH]  = concentration of NaOH

VNaOH = volume of NaOH

From the balanced reaction equation;

2 moles of NaOH reacts with 1 mole of H2SO4

2nH2SO4 = nNaOH

2[H2SO4] × VH2SO4 =  [NaOH] × VNaOH

[H2SO4] =   [NaOH] × VNaOH/ 2× VH2SO4

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