A certain substance X condenses at a temperature of 120.7 degree C. But if a 500, g sample of X is prepared with 55.4 g of urea (NH_2)_2 CO) dissolved in it, the sample is found to have a condensation point of 125.2 degree C instead. Calculate the molal boiling point elevation constant K_b of X. Round your answer to 2 significant digits.

Answer:

If an atom is in column V (or 15), it will most likely gain 3 electrons to fulfill the octet rule.

Explanation:

The octet rule defines the property that atoms have to complete their last energy level with eight electrons to achieve stability through an ionic, covalent or metallic bond.

The pair of electrons that are transferred or gained belong to the last shell of the atom. If an atom is in column V (or 15), it means that it has 5 electrons in its last shell. So an atom in this group is more likely to gain 3 electrons to achieve stability than to lose the 5 electrons it has.

If an atom is in column V (or 15), it will most likely gain 3 electrons to fulfill the octet rule.

A.  Gain 3 electrons

The octet rule defines the property that atoms have to complete their last energy level with eight electrons to achieve stability through an ionic, covalent or metallic bond.

The pair of electrons that are transferred or gained belong to the last shell of the atom. If an atom is in column V (or 15), it means that it has 5 electrons in its last shell. So an atom in this group is more likely to gain 3 electrons to achieve stability than to lose the 5 electrons it has.

Thus, correct option is A.

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Answer:

H^+(aq) + OH^-(aq) —> H2O(l)

Explanation:

We'll begin by writing the balanced equation for the reaction.

2HCl(aq) + Ca(OH)2(aq) —> CaCl2(aq) + 2H2O(l)

Ca(OH)2 is a strong base and will dissociates as follow:

Ca(OH)2(aq) —> Ca^2+(aq) + 2OH^-(aq)

HCl is a strong acid and will dissociates as follow:

HCl(aq) —> H^+(aq) + Cl^-(aq)

Thus, In solution a double displacement reaction occurs as shown below:

2H^+(aq) + 2Cl^-(aq) + Ca^2+(aq) + 2OH^-(aq) —> Ca^2+(aq) + 2Cl^-(aq) + 2H2O(l)

To get the net ionic equation, cancel out Ca^2+ and 2Cl^-

2H^+(aq) + 2OH^-(aq) —> 2H2O(l)

H^+(aq) + OH^-(aq) —> H2O(l)

Answer:

Al2(SO4)3 is the limiting reactant

Explanation:

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

3Ba + Al2(SO4)3 → 2Al + 3BaSO4

Next, we shall determine the mass of Ba and the mass of Al2(SO4)3 that reacted from the balanced equation. This is illustrated below:

Molar mass of Ba = 137g/mol

Mass of Ba from the balanced equation = 3 x 137 = 411g

Molar mass of Al2(SO4)3 = 2x27 + 3[32 + (16x4)]

= 54 + 3[32 + 64]

= 54 + 3[96]

= 54 + 288 = 342g/mol

Mass of Al2(SO4)3 from the balanced equation = 1 x 342 = 342g

Summary:

From the balanced equation above,

411g of Ba reacted with 342g of Al2(SO4)3.

Finally, we shall determine the limiting reactant as follow:

From the balanced equation above,

411g of Ba reacted with 342g of Al2(SO4)3.

Therefore, 8g of Ba will react with

= (8 x 342/411 = 6.66g of Al2(SO4)3.

From the calculations made above, we can see that it will take a higher mass of Al2(SO4)3 i.e 6.66g than what was given i.e 2.8g to react completely with 8g of Ba.

Therefore, Al2(SO4)3 is the limiting reactant and Ba is the excess reactant.

Answer: HA has lowest pH and it is the most acidic as compared to the rest of given acids.

Explanation:

We know that relation between [tex]pK_a[/tex] and [tex]K_a[/tex] is as follows.

       [tex]pK_a = -log K_a[/tex]

This means that more is the value of [tex]K_a[/tex], smaller will be the [tex]pK_a[/tex]. Also, more is the value of [tex]K_a[/tex] smaller will be the pH of a solution.

As, larger is the value of [tex]K_a[/tex] more negative will be the [tex]pK_a[/tex] value. Hence, stronger will be the acid.

In the given options, HA has the smallest [tex]pK_a[/tex] value.

Therefore, we can conclude that HA has lowest pH and it is the most acidic as compared to the rest of given acids.

Answer:

Boron

Explanation:

Answer: a. boron

Explanation: bc the Boron Family is named after the first element in the family. atoms in this family have 3 valence electrons. this family includes a metalloid (boron), and the rest are metals.

Answer:

Your question is complex, because I think you wrote it wrong.

Although in front of this what I can help you is that the carbons are associated between a single, double or triple union.

This depends on whether they are attached to more or less carbons or hydrogens, the carbons have the possibility of joining 4 radicals, both other carbons and hydrogens.

Simple junctions talks about compound organisms called ALKANS.

The double unions, in organic these compounds are called as ALQUENOS.

And as for the tertiary unions, the organic chemistry names them as ALQUINOS.

These compounds that we write, a simple union, the less energy, the less this union, that is why the triple bond is the one that contains the most energy when breaking or destroying it in a reaction.

Explanation:

In a chemical compound the change of these unions if we modified them we would generate changes even in the classifications naming them as well as different compounds and not only that until they change their properties

Answer:

Answer:

The first should be left asis because carbon already has 4 bonds/8 electrons

The second needs to have a double bond to give carbon 4 bonds/8 electrons

The third must have a triple bong between the carbons to give them both 4 bonds/8 electrons

Explanation:

Make sure Hydrogen only has 1 bond/2 electrons at all times. Carbon needs a total of 4 bonds/8 electrons

Answer:

140 T or thymine base

Explanation:

Adenine pairs with Thymine in DNA thus the number of adenine will always equal number of thymine (unless some sort of mutation), therefore in this problem you have 140 A so you have 140 T as well. Remember: Adenine (A) and Thymine(T) is equal, & Cytosine (C) and Guanine (G) is equal

Answer:c

Explanation: rusting, burning and fuzzing are all examples of chemical reactions/changes.

Answer:

if magnesium looses five moles of electrons, oxygen will also gain five moles of electrons.!

Explanation:

Oxidation refers to the loss of electrons. Any specie that looses electrons in a redox reaction is said to be the reducing agent. Hence the reducing agent participates in the oxidation half equation. In this case, magnesium is the reducing agent.

Reduction has to do with the gain of electrons. The oxidizing agent participates in the reduction half equation. Hence the oxidizing agent is reduced in the redid reaction. The reducing agent in this case is the oxygen molecule.

Oxidation half equation;

Mg(s)-----> Mg^2+(aq) + 2e

Reduction half equation;

O2(g) + 2e ------> 2O^2-(aq)

From the balanced reaction equation, two moles of electrons is transferred.

Hence if magnesium looses five moles of electrons, oxygen will also gain five moles of electrons.

Answer:

The correct answer is 66.35 kilograms.

Explanation:

Based on the data given in the question, the energy consumed by the body of a human being is 50%. Based on the given data, the energy consumed in a day is 8000 kJ, 50 percent is the energy transfer efficiency. Thus, the consumption of total energy is 4000 kJ, and for the transformation of ADP to ATP, the energy involved is 30.6 kJ per mole.  

Hence, the total ATP produced in the process is,  

ATP = 4000 kJ / 30.6 kJ/mol

= 130.7189 mol.  

Thus, with the energy transfer efficiency of 50 percent, the total moles of ATP produced is 130.7 mol.  

The mass of ATP can be calculated by using the formula,  

moles = mass/molecular mass

The molecular mass of ATP is 507.18 g per mol

Now by putting the values we get,  

mass of ATP = 130.7189 mol * 507.18 g/mol

= 66298.011 g or 66.298 kg

It is mentioned that human comprise 50 g of ATP or 0.05 kg of ATP. Therefore, the sum of the available ATP will be.  

= Total production of ATP + Total ATP available

= 66.298 kg + 0.05 kg

= 66.348 kg

Hence, the sum of the ATP that is turned over by a resting human in a day is 66.35 kg.  

Answer:

Explanation:

Calcium oxide is fromed by the decomopostion of CaCO3 at high temperature.

CaCO3   ------> CaO  +CO2

Hope this helps you

Answer:

well the MF is 224.78 g/mol

Explanation:

just times them all by the molor mass and divide it by 3

Answer:

(D.)

The core of the pyruvate dehydrogenase complex is made up of eight catalytic trimers that make up the E2 component.

Explanation:

Eight trimers assemble as a hollow truncated cube, which forms the core of the multi-enzyme complex, known as the E2 complex in human pyruvate dehydrogenase complex.

Answer:

Exothermic reaction.

Explanation:

Answer:

(1R,3R)-1-ethyl-3-methylcyclohexane.

Explanation:

NOTE: The question is not complete since we do not have the diagram to the chemical structure in the question. Kindly check the attached picture for the diagram of the chemical structure.

So, in order to name Enantiomers or chemical structure through the use of the R,S system requires series of rules and regulations to follow for the proper naming.

There is an ethyl attached to the compound as the first substituents and methyl at the third which are the secondary prefix.

=> The longest chain is 6, thus the compound has hexane as the root compound.

=> It is (1R,3R) because when we draw from the highest substituents to the lower substituents, this is done in a clockwise direction.

Answer:

The brain

Explanation:

With all those instructions the body recqures to respond to it must be so

Hope it helps

Answer:

Concepts and reason

Lewis structure is a structure that explains the bonding between atoms of a molecule and lone pair of electrons that is present in the molecule is called a Lewis structure.

With the help  of Lewis structure the electronic geometry of a molecule can be determine.

Fundamentals

According to Lewis structure, every atom and their position in the structure of a molecule by using its chemical symbol.

Lines connecting the atoms that are bonded to them are drawn. Lone pairs are expressed by pairs of dots and are located beside the atoms.

Lewis structure  of [tex]H_{2}O[/tex] is, the total number of valence electrons is eight in [tex]H_{2}O[/tex].

Answer:

a) ammonium ion

b) amide ion

Explanation:

The order of decreasing bond angles of the three nitrogen species; ammonium ion, ammonia and amide ion is NH4+ >NH3> NH2-. Next we need to rationalize this order of decreasing bond angles from the valence shell electron pair repulsion (VSEPR) theory perspective.

First we must realize that all three nitrogen species contain a central sp3 hybridized carbon atom. This means that a tetrahedral geometry is ideally expected. Recall that the presence of lone pairs distorts molecular structures from the expected geometry based on VSEPR theory.

The amide ion contains two lone pairs of electrons. Remember that the presence of lone pairs causes greater repulsion than bond pairs on the outermost shell of the central atom. Hence, the amide ion has the least H-N-H bond angle of about 105°.

The ammonia molecule contains one lone pair, the repulsion caused by one lone pair is definitely bless than that caused by two lone pairs of electrons hence the bond angle of the H-N-H bond in ammonia is 107°.

The ammonium ion contains four bond pairs and no lone pair of electrons on the outermost nitrogen atom. Hence we expect a perfect tetrahedron with bond angle of 109°.

Answer:

Mass ratio of sulfur and oxygen in compounds A and B is 3:2 which confirms that the mass ratios in the two compounds are simple multiples of each other

Explanation:

This question seeks to establish/confirm the law of multiple proportions which  posits that elements combine to form different substances which are whole number multiples of each other. Best example of this plays out in the formation of several oxides of the same element. Looking at the ratio in which the elements combine in each of the oxides, we can assume that these ratios are simple whole number multiples of each other.

Now back to the question.

In substance A, we have 6 g of sulfur combining with 5.99 g of oxygen

Now, lest us calculate the ratio of the mass of sulfur to that of oxygen = 6g/5.99g = 1

Now let us calculate the mass ratio of sulfur to oxygen in the second compound = 8.6/12.88 = 0.668

Now the ratios in both compounds are 1 to 0.668. 0.668 to fraction is approximately 1/1.5.

So therefore, the ratio we are having would be 1:1/1.5 or 1:0.668

This is same as 1/(1÷1.5) which is 1.5/1 or simply 3/2

This gives a ratio of approximately 1.5 to 1 or 3 to 2

The ratio 3 to 2 indicates that the mass ratios in both com pounds are simple multiples of each other

Answer:

True

Explanation:

Answer: The molecular formula for the given organic compound is [tex]C_{18}H_{20}O_2[/tex]

Explanation:

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

[tex]C_xH_yO_z+O_2\rightarrow CO_2+H_2O[/tex]

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of [tex]CO_2=39.61g[/tex]

Mass of [tex]H_2O=9.01g[/tex]

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 39.61 g of carbon dioxide, [tex]\frac{12}{44}\times 39.61=10.80g[/tex] of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in 9.01 g of water, [tex]\frac{2}{18}\times 9.01=1.00g[/tex] of hydrogen will be contained.

Mass of oxygen in the compound = (13.42) - (10.80 + 1.00) = 1.62 g

To formulate the empirical formula, we need to follow some steps:

Moles of Carbon = [tex]\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{10.80g}{12g/mole}=0.9moles[/tex]

Moles of Hydrogen = [tex]\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{1g}{1g/mole}=1moles[/tex]

Moles of Oxygen = [tex]\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{1.62g}{16g/mole}=0.10moles[/tex]

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.10 moles.

For Carbon = [tex]\frac{0.9}{0.10}=9[/tex]

For Hydrogen = [tex]\frac{1}{0.10}=10[/tex]

For Oxygen = [tex]\frac{0.10}{0.10}=1[/tex]

The ratio of C : H : O = 9 : 10 : 1

Hence, the empirical formula for the given compound is [tex]C_9H_{10}O[/tex]

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is :

[tex]n=\frac{\text{Molecular mass}}{\text{Empirical mass}}[/tex]

We are given:

Mass of molecular formula = 268.34 g/mol

Mass of empirical formula = 134 g/mol

Putting values in above equation, we get:

[tex]n=\frac{268.34g/mol}{134g/mol}=2[/tex]

Multiplying this valency by the subscript of every element of empirical formula, we get:

[tex]C_{(9\times 2)}H_{(10\times 2)}O_{(1\times 2)}=C_{18}H_{20}O_2[/tex]

Thus, the molecular formula for the given organic compound is [tex]C_{18}H_{20}O_2[/tex].

Answer:

10 g of CO2

Explanation:

Equation of the reaction:

CH3(CH2)6CH3 + 17O2 ----> 18H2O + 8CO2

Fom the above balanced equation,

1 mole of Octane gas reacts with 17 moles of oxygen gas to produce 8 moles of CO2

Molar mass of Octane = 114 g/mol

Molar mass of oxygen gas = 32 g/mol

Molar mass of CO2 = 44 g/mol

Therefore, 114 g of Octane reacts completely with 17 * 32g (= 544 g) of oxygen to produce 8 * 44 g(=352g) of CO2.

From the given mass of reactants;

3.4 g of Octane will react with (544 * 3.4)/114 g of oxygen = 16.22g of oxygen.

Therefore oxygen is the limiting reactant.

15.6 g of oxygen will react with (114 * 15.6)/544 g of CO2 = 3.27 g of octane.

Mass of CO2 produced will be

(352 * 15.6)/544 = 10 g of CO2

Answer:

balanced because the total number of oxygen atoms is 3.

Answer: [tex]2(NH_4)_3PO_4(aq)+3CaS(aq)\rightarrow Ca_3(PO_4)_2(aq)+3(NH_4)_2S(s)[/tex] is a double displacement reaction (dr).

Explanation:

A double displacement reaction (dr) is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.

[tex]2(NH_4)_3PO_4(aq)+3CaS(aq)\rightarrow Ca_3(PO_4)_2(aq)+3(NH_4)_2S(s)[/tex]

Combination reaction (C) is defined as the reaction where substances combine in their elemental state to form a single compound.

Single displacement reaction (sr) is defined as the reaction where more reactive element displaces a less reactive element from its chemical reaction.

Decomposition reaction (d) is defined as the reaction where a single substance breaks down into two or more simpler substances.

Combustion (Co) is a type of chemical reaction in which hydrocarbons burn in the presence of oxygen to form carbon dioxide and water along with heat.

Answer:

5

Explanation:

Answer:

5

Explanation:

The voltage of an electrolytic cell with copper and magnesium electrodes is 2.71 v. Therefore, option B is correct.

The electrolytic cell is a type of cell that performs a redox reaction while using electrical energy. When electrical energy is applied, a redox reaction occurs in molten NaCl. It is therefore an electrolytic cell.

An electrolyte, two electrodes, and an electrolytic cell make up an electrolytic cell (a cathode and an anode). The electrolyte is typically a mixture of ions that have been dissolved in water or another solvent. Electrolytes can also be molten salts, like sodium chloride.

The standard reduction potential, E° of the metals are as below:

Mg²⁺ + 2e⁻ ⇌  Mg; E° = -2.372

Cu²⁺ + 2e⁻ ⇌  Cu; E° = +0.337

Therefore, magnesium has the the lower E°, it will serve as the anode in the electrolytic cell while copper will serve as the cathode.

At the anode; Mg ⇌  Mg²⁺ + 2e⁻, E° = -2.372

At the cathode; Cu²⁺ + 2e⁻ ⇌  Cu, E° = +0.337

EMF of the cell = E° cathode - E° anode

= 0.337 - (-2.372) = 2.71 V

Therefore, EMF of the cell is 2.71 V

Thus, option B is correct.

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Answer: The molecular formula for the carcinogenic form of asbestos [tex]Mg_3Si_2H_4O_9[/tex]

Explanation:

a) If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of Mg = 26.31 g

Mass of Si= 20.20 g

Mass of H= 1.45 g

Mass of O= (100-(26.31+ 20.20+ 1.45)) =  52.04 g

Step 1 : convert given masses into moles

Moles of Mg=[tex]\frac{\text{ given mass of Mg}}{\text{ molar mass of Mg}}= \frac{26.31g}{24g/mole}=1.10moles[/tex]

Moles of Si=[tex]\frac{\text{ given mass of Si}}{\text{ molar mass of Si}}= \frac{20.20g}{28g/mole}=0.72moles[/tex]

Moles of H=[tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{1.45g}{1g/mole}=1.45moles[/tex]

Moles of O=[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{52.04g}{16g/mole}=3.25moles[/tex]

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For Mg = [tex]\frac{1.10}{0.72}=1.5[/tex]

For Si =[tex]\frac{0.72}{0.72}=1[/tex]

For H=[tex]\frac{1.45}{0.72}=2[/tex]

For O =[tex]\frac{3.25}{0.72}=4.5[/tex]

The ratio of  Mg : Si: H: O = 1.5 : 1 : 2 : 4.5

Converting them into whole numbers :

The ratio of  Mg : Si: H: O = 3 : 2 : 4 : 9

Hence the empirical formula is [tex]Mg_3Si_2H_4O_9[/tex]

Empirical mass =[tex]3\times 24+2\times 28+4\times 1+9\times 16=276g[/tex]

Molecular mass = 277 g

[tex]n= \frac{\text {Molecular mass}}{\text {Empirical mass}}=\frac{277}{276}=1[/tex]

Thus molecular formula =[tex]1\times Mg_3Si_2H_4O_9=Mg_3Si_2H_4O_9[/tex]

Answer:

b :)

Explanation:

an exothermic reaction is when heat/light is produced. heart is produced from this reaction so it is exothermic

The correct answer is option c. The reaction between salt and water is endothermic.

Chemical reaction

Salt is a hygroscopic material that attracts water and heat from its surroundings. This is why leather shoes are "dry" and wrinkled when covered with salt. This type of reaction is known as an endothermic reaction, which is a chemical reaction that absorbs heat.

Endothermic reaction: A chemical reaction that absorbs heat is called an endothermic reaction. The temperature will drop. For example, (i) heating nitrogen and oxygen together to a temperature of about 3000 ° C produces nitrogen oxide gas. N2 + O2 + heat → 2NO (g)

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Answer:

[tex]n_N=0.041molN[/tex]

Explanation:

Hello,

In this case, for this mole-mass relationship, we are able to compute the moles of nitrogen atoms by firstly obtaining the moles of the given compound, considering its molar mass that is 194 g/mol:

[tex]n_{C_8H_{10}O_2N_4}=2.0gC_8H_{10}O_2N_4*\frac{1molC_8H_{10}O_2N_4}{194gC_8H_{10}O_2N_4} =0.01molC_8H_{10}O_2N_4[/tex]

Then, by knowing that one mole of the given compound has four moles of nitrogen atoms, we apply the following relationship:

[tex]n_N=0.01molC_8H_{10}O_2N_4*\frac{4molN}{1molC_8H_{10}O_2N_4} \\\\n_N=0.041molN[/tex]

Best regards.