Match each vocabulary word with its definition. match the items in the left column to the items in the right column. 1 . periodicity unlike charges 2 . shell like charges 3 . nonmetals charge on a neutron 4 . noble gases location of an electron 5 . neutral high ionization energies 6 . repel repeating nature of atomic structure 7 . attract least reactive family

Answer:

Exothermic

Explanation:

An exothermic reaction results when the energy released by the formation of products is greater than the energy required to break the bonds in the reactants.

Answer:

B) Changing the enzyme concentration

The slowest way to regulate a reaction in a metabolic pathway is by changing the enzyme concentration.

It is series of chemical reactions that occurred in the cell. Metabolites referred to as species participating in an enzymatic reaction.

Role of Enzymes:

Enzymes act as catalysts – they allow a reaction to proceed more rapidly – and they also allow the regulation of the rate of a metabolic reaction

The binding of an enzyme to its substrate lowers the activation energy of the reaction. If an enzyme is present, the amount of energy needed to make a product is lowered.

In metabolic reactions there is transfer of electrons from one compound to another by processes catalyzed by enzymes.

Enzymes participates in increasing and decreasing the metabolism process inside our body. On increasing the substrate concentration, the rate of enzyme activity also increases.

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Answer:

The ones with 8 protons

Explanation:

Since there are two of them with 8 protons, we can assume they are the same element. The first 8 proton element has 10 neutrons while the second has 11. This makes them isotopes of one another

Answer:

Explanation:

1) Data:

a) V₁ = 38.2 liter

b) P₁ = 91 psi

c) V₂ = 77.4 liter

d) P₂ = ?

2) Formula:

According to Boyle's law, at constant temperature, the pressure and volume of a fixed amount of gas are inversely related:

3) Solution:

Answer:

a. have an excess number of neutrons.

Explanation:

Every atomic nucleus  have a specific neutron/proton ratio that makes them stable. Any nucleus with a neutron/proton ratio that differs from the stability ration will become unstable. An unstable nucleus will split up and emit small particles of matter and/electromagnetic ionizing radiation. This makes an atom radioactive.

Therefore, an atom with excess number of neutrons is a radioactive isotope.

S + 2e⁻ → S²⁻ (sulfur will gain electrons)

Mg - 2e⁻ → Mg²⁺ (magnesium will lose electrons)

Magnesium is a metal which tends to give electrons which are received by the sulfur, which is a nonmetal and tends to gain electrons.

Answer: The atom which gains electrons is sulfur

Explanation:

Oxidation reaction is defined as the chemical reaction in which an atom looses its electrons. The oxidation number of the atom gets increased during this reaction.

[tex]X\rightarrow X^{n+}+ne^-[/tex]

Reduction reaction is defined as the chemical reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.

[tex]X^{n+}+ne^-\rightarrow X[/tex]

For the given chemical equation:

[tex]Mg+S\rightarrow MgS[/tex]

Oxidation half reaction:  [tex]Mg\rightarrow Mg^{2+}+2e^-[/tex]

Reduction half reaction:  [tex]S+2e6-\rightarrow S^{2-}[/tex]

Hence, the atom which gains electrons is sulfur

Answer:

2HNO3 + Ca(OH)2 → 2H2O + Ca(NO3)2

Explanation:

HNO3 + Ca(OH)2 → ?

This is an acid-base reaction. It is also a double displacement reaction, in which the positive ions change partners.

Thus, H pairs with OH and Ca pairs with NO3.

HNO3 + Ca(OH)2 → HOH + Ca(NO3)2

HOH is our old friend, H2O (water) so, after balancing atoms, the equation becomes:

2HNO3 + Ca(OH)2 → 2H2O + Ca(NO3)2

Hydrogen fuel cells burn with Oxygen and produces Water.

It is commonly used to produce electricity.

Answer:

with oxygen to form water

Explanation:

In a flame of pure hydrogen gas, burning in air, the hydrogen (H2) reacts with oxygen (O2) to form water (H2O) and releases heat. If carried out in atmospheric air instead of pure oxygen (as is usually the case), hydrogen combustion may yield small amounts of nitrogen oxides, along with the water vapor.

Answer:

q < 0, w > 0, the sign of ΔE cannot be determined from the information given

Explanation:

Determination of sign of q

Temperature of the water bath before the reaction = 25 °C

Temperature of the water bath after the completion of the reaction = 28 °C

After the completion of the reaction, temperature of the water bath is increased that means heat is released during the reaction and flows out of the system.

If heat is absorbed by the system, then q is indicated by positive sign and if heat is released by the system, then q is indicated by negative sign.

As in the given case, heat is released by the system, so sign of q is negative, or q < 0

Determination of sign of w

After the completion of the reaction, piston moved downward, that means volume of the system decreases or compression occur. During the compression, work is done on the system.

if work is done on the system, sign of w is positive.

If work is done by the system, sign of w is negative.

In the given case, work is done on the system, therefore sign of w is positive, or w > 0

Determination of sign of ΔE

Relationship between ΔE, q and w is given by first law of thermodynamics:

ΔE = q + w

In this case, q is positive and w is negative, so the sign of ΔE depends of magnitude of q and w. As magnitude of w and q cannot be determined in this case, thus, the given information is insufficient for the determination of sign of ΔE.

So, among the given option, option c is correct.

q < 0, w > 0, the sign of ΔE cannot be determined from the information given

The best option that describes the signs of q, w, and ΔE for this reaction is q < 0, w > 0, the sign of ΔE cannot be determined from the information given.

Option C is correct.

From the given information, if we examine the mixture of the gases A2 and B2 and take them to be the system, and the slender metal cylinder as well as the water bath to be the surroundings.

Then, we can infer that:

Hence, when the reaction is said to be completed, we are being informed from the question that the temperature increased. This implies that there is an outflow and release of heat away from the system. As such, when heat flows away from the system, the sign (q) will be negative.

For the work done (w):

When the reaction goes into completion, the movement of the piston downward indicates that there is a decrease in the volume of the system.

As such, work is done on the system, hence, the work done (w) is positive.

For the change in the internal energy ΔE. If we look at the first law of thermodynamics, we know that:

ΔE = q + w

here,

However, the sign of ΔE largely depends on the magnitude of q and w. We can infer that there is little information given for the determination of ΔE

Therefore, we can conclude that q < 0 since it is negative, w > 0 since it is positive and the sign of ΔE cannot be determined from the information given.

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Answer:

N₂(g) + 2O₂(g) → 2NO₂(g).

Explanation;

Photo-chemical smog is considered to be a new type of air pollution that is basically a mixture of pollutants that are formed when volatile compounds of organic nature (Hydrocarbons) react and Nitrogen oxides  (NOx) react with solar radiations of sun and lead to the formation of photochemical smog that looks like a brown haze in the skies of cities.

pounds (VOCs) react to sunlight, creating a brown haze above cities. It tends to occur more often in summer, because that is when we have the most sunlight.

As mentioned in the question, the formation of smog involves a series of reactions:

N2(g) + O2(g)—>2NO(g)

2NO(g) + O2(g)—>2NO2(g)

NON(g) light_» NO(g) + O(g)

O2(g)+O(g)—>Os(9)

NO(g) + O2(g)—>NO2(g) + O2(g)

If we combine all these chemical equations, it gives an answer as:

N₂(g) + 2O₂(g) → 2NO₂(g).

This is because main components involve in the formation of smog is initial N2 and 2 molecules of O2.

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Answer:

D

Explanation:

Edge 2020

Answer:

Explanation:

1) Dissociation:

Since HCl is a strong acid, it dissociates 100% in water to form hydronium (H₃O⁺) and chloride (Cl⁻) ions, as per this chemical equation:

2) Concentrations:

Hence, each mole of HCl molecules yields 1 mol of hydronium ( H₃O⁺) and 1 mol of chloride (Cl⁻) ions.

Thus, [HCl] = [H₃O⁺] = [Cl⁻] = 0.01 M

3)  Conclusion: the concentraion of hydronium ions in a 0.01 M solution of HCl is 0.01 M

Answer : The volume of [tex]CO_2[/tex] will be, 514.11 ml

Explanation :

The balanced chemical reaction will be,

[tex]HCO_3^-+HCl\rightarrow Cl^-+H_2O+CO_2[/tex]

First we have to calculate the  mass of [tex]HCO_3^-[/tex] in tablet.

[tex]\text{Mass of }HCO_3^-\text{ in tablet}=32.5\% \times 3.79g=\frac{32.5}{100}\times 3.79g=1.23175g[/tex]

Now we have to calculate the moles of [tex]HCO_3^-[/tex].

Molar mass of [tex]HCO_3^-[/tex] = 1 + 12 + 3(16) = 61 g/mole

[tex]\text{Moles of }HCO_3^-=\frac{\text{Mass of }HCO_3^-}{\text{Molar mass of }HCO_3^-}=\frac{1.23175g}{61g/mole}=0.0202moles[/tex]

Now we have to calculate the moles of [tex]CO_2[/tex].

From the balanced chemical reaction, we conclude that

As, 1 mole of [tex]HCO_3^-[/tex] react to give 1 mole of [tex]CO_2[/tex]

So, 0.0202 mole of [tex]HCO_3^-[/tex] react to give 0.0202 mole of [tex]CO_2[/tex]

The moles of [tex]CO_2[/tex] = 0.0202 mole

Now we have to calculate the volume of [tex]CO_2[/tex] by using ideal gas equation.

[tex]PV=nRT[/tex]

where,

P = pressure of gas = 1.00 atm

V = volume of gas = ?

T = temperature of gas = [tex]37^oC=273+37=310K[/tex]

n = number of moles of gas = 0.0202 mole

R = gas constant = 0.0821 L.atm/mole.K

Now put all the given values in the ideal gas equation, we get :

[tex](1.00atm)\times V=0.0202 mole\times (0.0821L.atm/mole.K)\times (310K)[/tex]

[tex]V=0.51411L=514.11ml[/tex]

Therefore, the volume of [tex]CO_2[/tex] will be, 514.11 ml

Answer:

propanoic acid forms hydrogen bonded dimers and 1-butanol does not.

Explanation:

Propanoic acids will have a higher boiling point because it forms dimers.

The two compounds have hydrogen bonds as their predominant intermolecular bonds. The intermolecular determines a lot about the physical properties of a substance such as it's viscosity, boiling point, melting point etc.

The two compounds have hydrogen bonds which are bonds that occur between between hydrogen and a more electronegative atom. The electronegative atoms are usually oxygen,nitrogen and fluorine.

In a compound of 1-butanol, we have just a single hydrogen bond between the hydrogen on one compound and the oxygen on the hydroxyl group of another one.

For, propanoic acids, dimerization occurs. Here, we have two hydrogen bonds. The alkanoic acid functional group furnishes the bond. This bond forms between the carbonyl group and hydrogen on a compound and the hydroxyl group and another hydrogen on the same compound.

Answer:

This ion is in an octahedral geometry.

See the diagram attached for the Lewis Dot Structure of the iodide hexafluoride cation [tex]\rm {IF_6}^{+}[/tex]. (Created with Google Drawings.)

Note that in this diagram,

Explanation:

The iodine in [tex]\rm {IF_6}^{+}[/tex] forms an expanded octet. There are twelve valence electrons in total around this atom.

Overall, there needs to be [tex]6 \times 1 + 5 + 1= 12[/tex] more electrons for seven atoms to achieve an octet. They will form half that number of chemical bonds. That's [tex]12 / 2 = 6[/tex] bonds.

Now consider: what will be the geometry of this ion? There are six chemical bonds but no lone pair around the central iodine atom. The six [tex]\mathrm{I-F}[/tex] bonds repel each other equally. They will stay as far apart from each other as possible. As a result, the shape of the ion will be octahedral. Each of the fluorine atoms occupies a vertex.

The enthalpy of neutralization of HCl and NaOH is 8.18 kJ/mol.

The enthalpy of neutralization is the heat released or absorbed when an acid and a base react to form one mole of water. In this case, the reaction is between hydrochloric acid (HCl) and sodium hydroxide (NaOH).

From the given information, 87 cm3 of 1.6 mol dm-3 HCl is neutralized by 87 cm3 of 1.6 mol dm-3 NaOH. The temperature rose from 298 K to 317.4 K.

To calculate the enthalpy change, we can use the formula:

Enthalpy change of neutralization = (mole of limiting reactant) x (heat evolved per mole of reaction)

From the balanced equation: HCl(aq) + NaOH(aq) -> NaCl(aq) + H2O(l)

This means that 1 mole of HCl reacts with 1 mole of NaOH to produce 1 mole of water. So, the heat evolved per mole of reaction is equal to the enthalpy change of neutralization.

Now, let's calculate the mole of the limiting reactant:

Given volume of HCl = 87 cm3 = 87 x 10-3 dm3

Given molarity of HCl = 1.6 mol dm-3

Mole of HCl = volume x molarity = (87 x 10-3) x 1.6 = 0.1392 mol

Since the mole of HCl and NaOH are equal, the mole of the limiting reactant is 0.1392 mol.

To determine the heat evolved per reaction, we need to divide the heat evolved by the mole of reaction:

Given temperature change = 317.4 K - 298 K = 19.4 K

Given the specific heat capacity of water = 4.18 J/K g

Assuming the density of the solutions is the same as water, we can use the mass of the solutions:

Mass of solution = volume x density = 87 x 10-3 dm3 x 1 g/cm3 = 87 g

Now, we can calculate the heat evolved:

Heat evolved = mass x specific heat capacity x temperature change = 87 g x 4.18 J/K g x 19.4 K = 8,177.56 J/mol

Convert the heat evolved from Joules to kilojoules:

The heat evolved = 8,177.56 J/mol = 8.18 kJ/mol (rounded to 2 decimal places)

Therefore, the enthalpy of neutralization of HCl and NaOH is 8.18 kJ/mol.

Answer:

C. If it is tested and the evidence does not support it.

Explanation:

A hypothesis is more less a scientific guess. Before such a guess or prediction is made, empirical observations and deductions are first made. It is from the result of the observations that a hypothesis statement is made.

For a hypothesis to become widely adopted and accepted, it must be testable within the limits of the experiment as described by the proposer. When subjected to test and it agrees, the status of a hypothesis can be upgraded.

If the hypothesis is tested and evidence contrasts the result being sort for, a hypothesis will be discarded.

Answer:

177.8kJ/mol

Explanation:

In this reaction, the heat of decomposition is the same as the heat of formation. This is a decomposition reaction.

Given parameters:

ΔHf CaCO₃ = -1206.9kJ/mol

ΔHf CaO = −635.6 kJ/mol

ΔHf CO₂ = −393.5 kJ/mol

The heat of decomposition =

                     Sum of ΔHf of products - Sum of ΔHf of reactants

The equation of the reaction is shown below:

     CaCO₃ → CaO + CO₂

The heat of decomposition = [ -635.6 + (-393.5)] - [−1206.9 ]

                                             = -1029.1 + 1206.9

                                             = 177.8kJ/mol

The heat of decomposition given by the difference in the ΔH of product and reactant is 177.8 kj/mol

Given the equation for the decomposition process :

The heat for the decomposition process is the difference of the sum of heat of the product and the heat of the reactant :

Reactant :

Product :

Heat of decomposition :

Heat of decomposition = - 1029.1 - (- 1206.9)

Heat of decomposition = -1029.1 + 1206.9 = 177.8 kj/mol

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The molar mass of the unknown compound under the given conditions, deemed to behave as an ideal gas, is approximately 176.124 g/mol. We determined this via the ideal gas law, which allowed us to find the number of moles, and subsequently the molar mass through division of the compound's mass by the number of moles.

The problem involves calculating the molar mass of an unknown compound acting as an ideal gas under specific conditions. We begin by using the ideal gas law (PV = nRT), but we rearrange it to find the number of moles (n = PV/RT). Given the pressure (P = 1.00 atm), volume (V = 2010 mL or 2.01 L), and temperature in degrees Celsius (which must be converted to Kelvins, T = 180 + 273 = 453 K), and knowing the gas constant (R = 0.0821 L.atm/mol.K), we can calculate n.

Once we have the number of moles, we can find the molar mass by dividing the mass of the compound (given as 2.73g) by the number of moles. Thus, the molar mass of the compound is found to be approximately 176.124 g/mol.

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Answer:

it will last I'll say about 12-19 or 20 hours

Explanation:

my explanation is it all depends on the time and the degrees because it can last for weeks (5-7) but it won't

float

hope that helps

Helium typically lasts about 12 to 24 hours in a latex balloon. This is due to helium's high effusion rate, meaning it escapes quickly through small pores in the latex material.

In a latex balloon, helium typically lasts about 12 to 24 hours. This is mainly due to the effusion rate of helium, which is quite high because helium is a very light gas. A gas's effusion rate relates to how quickly it escapes through small pores or openings.

The balloon material, which in this case is latex, can only contain the gas for so long before it starts to leak out. As shown in the given photographs, a helium-filled balloon noticeably deflated after just 12 hours, whereas the argon-filled balloon remained inflated due to argon's lower effusion rate.

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Answer: the correct answer is protein

Explanation:

Large proteins are not normally filtered by a healthy glomerural membrane.

Answer:

The inert sand

Explanation:

A control variable is the variable in which the experiment does not depend on. The outcome of the control variable does not in any way validate or invalidate an experimental procedure.

The student seeks to investigate the effect of different salts on melting point. He used NaCl, CaCl₂, K₂CO₃ and inert sand. The first three are salts. Sand is made up of silica, SiO₂ and it is not a salt. Therefore, the control variable here is the inert sand. Sand is highly unreactive and would not in any significant way help the investigation.

Answer: Fourth one which received inert sand.

Explanation:

A control variable is the one which remains unchanged in an experiment. It does not receive any treatment. It is considered as a benchmark or standard for comparison of changes occurring in the dependent or experimental variable.

According to the given situation, the fourth one is the correct option as the inert sand will not have any effect over the melting of ice. This can be useful for comparison of the effect of salts on the ice.

You start from butanal which will react with methyl magnesium bromide (Gringard reagent) forming a compound with a new carbon-carbon bond. After that using an acid media the magnesium bromide salt is eliminated with formation of the 2-pentanol.

Answer:

Explanation:because turtles will eventually get old and they will leave behind their family like the next generation

Final answer:

The maximum work obtainable from oxidizing 0.50 mol of methanol under standard conditions is -686 kJ. This calculation is done by multiplying the given Gibbs free energy (ΔG) for the reaction by the number of moles of methanol.

Explanation:

The student's question pertains to the calculation of the maximum work that can be obtained by oxidizing methanol under standard conditions, given the Gibbs free energy change (ΔG) of the reaction. To find this, you use the equation ΔG = -nFE, where 'n' is the number of moles of electrons transferred, 'F' is the Faraday constant (96,485 C/mol e-), and 'E' is the electromotive force (emf). However, since ΔG is already provided and is the amount of energy available to do work at constant temperature and pressure, the calculation in this case is simpler and does not require the use of Faraday constantor emf.

The reaction, as given, is 2 CH3OH(l) + 3 O2(g) → 2 CO2(g) + 4 H2O(g) with ΔG = -1372 kJ/mol for the oxidation of 1 mole of methanol.

To calculate the maximum work for 0.50 mol of methanol:

Multiply ΔG by the number of moles of methanol being oxidized (0.50 mol).

Work = -1372 kJ/mol * 0.50 mol = -686 kJ.

Therefore, the maximum work that can be obtained by oxidizing 0.50 mol of methanol under standard conditions is -686 kJ. The negative sign indicates that the reaction is exergonic, releasing energy that can be used to do work.

Answer:

A.

Explanation:

444 Ma

Answer:

444 ma is right

Explanation:

The order of increasing ionization energy of the elements are; Ca < Mg < Si < O.

Ionization energy is a periodic trend that decreases down the group but increases across the period.

Ionization energy decreases down the group due to addition of more shells and increased screening of outermost electrons by the inner electrons.

Ionization energy increases across the period due to increase in size of the nuclear charge.

Hence, the order of increasing ionization energy of the elements are; Ca < Mg < Si < O.

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Answer: (a) pH = 4.774, (b) pH = 4.811 and (c) pH = 4.681

Explanation: (a) pH of the buffer solution is calculated using Handerson equation:

[tex]pH=pKa+log(\frac{base}{acid})[/tex]

pKa for acetic acid is 4.76. concentration of base and acid are given as 0.95M and 0.92M. Let's plug in the values in the equation and calculate the pH of starting buffer.

[tex]pH=4.76+log(\frac{0.95}{0.92})[/tex]

pH = 4.76 + 0.014

pH = 4.774

(b) When 0.040 mol of NaOH (strong base) are added to the buffer then it reacts with 0.040 mol of acetic acid and form 0.040 mol of sodium acetate.

Original buffer volume is 1.00 L. So, the original moles of sodium acetate will be 0.95 and acetic acid will be 0.92.

moles of acetic acid after addition of NaOH = 0.92 - 0.040 = 0.88

moles of sodium acetate after addition of NaOH = 0.95 + 0.040 = 0.99

Let's again plug in the values in the Handerson equation:

[tex]pH=4.76+log(\frac{0.99}{0.88})[/tex]

pH = 4.76 + 0.051

pH = 4.811

(c) When 0.100 mol of HCl are added then it reacts with exactly 0.100 moles of sodium acetate(base) and form 0.100 moles of acetic acid(acid).

so, new moles of acetic acid = 0.92 + 0.100 = 1.02

new moles of sodium acetate = 0.95 - 0.100 = 0.85

Let's plug in the values in the equation:

[tex]pH=4.76+log(\frac{0.85}{1.02})[/tex]

pH = 4.76 - 0.079

pH = 4.681

The pH of the buffer can be calculated at each step using the Henderson-Hasselbalch equation, which requires the pKa of the acid and the ratio of the base to acid concentrations. When NaOH is added, it reacts with the acetic acid, changing this ratio and thus the pH. When HCl is added, it reacts with the acetate, again changing the ratio and pH.

The initial pH of the buffer can be calculated using the Henderson-Hasselbalch equation. This equation requires the pKa, which for acetic acid is 4.74, and the ratio of the concentrations of the base (CH3COONa, or acetate) and acid (CH3COOH, or acetic acid). So we have pH = pKa + log([base]/[acid]) = 4.74 + log(0.95/0.92) ≈ 4.75. That's the starting pH of the buffer.

Now, when we add 0.040 mol NaOH, it will react with the acetic acid, converting it to acetate and thus increasing the [base]/[acid] ratio. The change in pH can again be calculated via the Henderson-Hasselbalch equation: pH = 4.74 + log((0.95 + 0.040)/(0.92 - 0.040)). Then, when we add 0.100 mol HCl, it will react with the acetate, converting it back to acetic acid and thus decreasing the [base]/[acid] ratio, again resulting in a pH shift that you can calculate the same way.

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Answer:

Explanation:

The enthalpy of reaction is the change of enthalpy of the chemical reaction. It is equal to the heat released or absorbed during the chemical reaction.

The enthalpy of reaction is equal to the difference of the enthalpy at the end of the reaction and the enthalpy at the begining of the reaction.

Since the substances at the end are the products, and the substances at the begining are the reactants, this is equivalent to say that the enthalpy of reaction is equal to the enthalpy of formation for the products less the enthalpy of formation for the reactants.

In the form of equation that is:

The enthalpy of a reaction (ΔH_rxn) is calculated by subtracting the sum of the enthalpies of formation of the reactants from the sum of the enthalpies of formation of the products. This calculation uses Hess's Law and accounts for the stoichiometric coefficients in the balanced equation. As such, the enthalpy change can indicate whether a reaction is exothermic or endothermic.

The enthalpy of a reaction (ΔH_rxn) is determined using the enthalpies of formation (ΔH_f) for the reactants and products. According to Hess's Law, the enthalpy change of any chemical reaction is equal to the sum of the enthalpies of formation of the products minus the sum of the enthalpies of formation of the reactants. Mathematically, this is expressed as:

ΔH_rxn = ∑ΔH_f(products) - ∑ΔH_f(reactants)

The enthalpies of formation are multiplied by the respective number of moles of each substance (as given by their coefficients in the balanced chemical equation) before summing up. For example, in the combustion of methane:

The reaction releases 890.5 kJ at 25°C because the energy needed to break the chemical bonds in the reactants differs from the energy released when forming the bonds in the products, reflecting an exothermic process.