The pH of a 0.64 M solution of pyridine (C₅H₅N) is 9.52.
What is pH ?A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.
The equation for the protonation of the base pyridine is the following:
C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻ (1)
Kb = 1.7 × 10⁻⁹ (Given)
To calculate the pH of the solution we need to use the following equation:
pH + pOH = 14
pH = 14 - pOH
=14 - [-log[OH⁻]]
= 14 + log[OH⁻]
Now, we need to find the concentration of the OH⁻ ions. Since pyridine is a weak base, at the equilibrium we have (eq 1):
C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻
0.64 - x x x
After entering the values of [C₅H₅N] = 0.64-x, [C₅H₅NH⁺] = x, and [OH⁻] = x, into equation (2) we can find the concentration of OH⁻:
1.7 × 10⁻⁹ =[C₅H₅NH⁺] [OH⁻] / [C₅H₅N]
= x . x / 0.64-x
1.7 × 10⁻⁹ (0.64-x) - x² = 0
Solving the above quadratic equation for x, we have :
x₁ = -3.32 x 10⁻⁵x₂ = 3.32 x 10⁻⁵Now, We can calculate the pH, after taking the positive value, x₂, (concentrations cannot be negative) and entering into above equation :
pH = 14 + log[OH⁻]
= 14 + log (3.32 x 10⁻⁵)
= 9.52
Therefore, the pH of the solution of pyridine is 9.52.
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Which element tends to gain electrons to form an anion
A. S
B. Na
C. Mn
D. Ba
Answer:
A.) S
Explanation:
Anions form when elements have more electrons than protons. Some elements want to gain electrons because all elements desire a full octet (8 valence electrons). That being said, some elements are closer to a full octet by gaining electrons, whereas some are closer when they give up electrons.
As a general rule, as you move to the right across the period table, the number of valence electrons an element has increases. Therefore, on the right of the periodic table, these elements have a little less than 8 valence electrons. It makes sense that these elements want to gain those last few electrons to gain a full octet, rather than giving up electrons. Sulfur (S) has 6 valence electrons (located in the 16th column). To gain a full octet, it will gain two electrons and thus become an anion.
Na, Mn, and Ba are on the left of the periodic table, so they'd rather give up electrons than gain them (to become cations).
Na2 C6H6O7 (sodium hydrogen citrate)
Express the mass of sodium to three significant figures.
mNa =
The exact mass of one Na - atom is 22.98977 amu and thus, the weight of two sodium atoms in present in Na₂C₆H₆O₇ is 45.979539 g/mol.
What is Molar mass ?The molar mass of a substance is the mass in grams of 1 mole of the substance.
We can obtain a substance's molar mass by summing the molar masses of its component atoms.
Mass of one Na atom = 22.98977
Mass of two Na atom = 22.98977 x 2
= 45.97954
= 45.9 (up to 3 Significant figures)
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The chemist discovers a more efficient catalyst that can produce ethyl butyrate with a 78.0 % yield. How many grams would be produced from 7.45 g of butanoic acid and excess ethanol?
Express your answer in grams to three significant figures.
7.66g of ethyl butyrate is produced.
The reaction is
CH₃CH₂CH₂COOH + CH₃CH₂OH ----> CH₃CH₂CH₂COOCH₂CH₃
The molar mass of butanoic acid is 88.11g/molWe have 7.45g of butanoic acidThe moles of butanoic acid we have is 7.45/88.11 = 0.0845 molIf the yield is 100%, 1 mole of butanoic acid gives 1 mole of ethyl butyrateBut the reaction yield is 78%1 mole of butanoic acid gives 0.78 mole of ethyl butyrateFrom 0.0845 mol of butanoic acid we get 0.78 x 0.0845 = 0.66 mol of ethyl butyrate.
The molar mass of ethyl butyrate is 116.16g/mol
So 0.66 x 116.16 = 7.66g
7.66g of ethyl butyrate is produced.
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? If a weaker solution of sodium bicarbonate was used in beaker b, would that solution require more or less hydrochloric to neutralize it and why?
Answer:
less HCL acid is required to neutralize a weaker solution of base (sodium bicarbonate).
Explanation:
ements
tton
2 NH3 + 3 CuO -->3 Cu + N₂ + 3H₂O
In the above equation how many moles of N₂ can be made when 156.1 grams of CuO are
consumed?
Round your answer to the nearest tenth. If you answer is a whole number like 4, report
the answer as 4.0
Use the following molar masses. If you do not use these masses, the computer will mark
your answer incorrect.:
Element Molar Mass
Hydrogen 1
Nitrogen 14
Copper 63.5
Oxygen 16
Answer: The amount of moles that can be produced when 156.1 grams of CuO are consumed is .653 moles.
Explanation: The first thing to do is to convert the 156.1 grams of Copper(II) Oxide (CuO).
In order to convert the 156.1 grams of Copper(II) Oxide to moles we have to first calculate the molar mass of Copper(II) Oxide. This can be done by simply adding the Copper's molar mass, 63.5, to the Oxygen's molar mass, 16.
16 g + 63.5 g = 79.5 g
Once you have obtained the molar mass of the Copper (II) Oxide you can then proceed to convert the 156.1 grams from before into moles.
This is done by multiplying 156.1 grams by 1 mole / 79.5 grams.
[tex]156.1 g *1 moles/79.5 g = 1.96 moles[/tex]
Now that you have calculated the 1.96 moles of Copper(II) Oxide, you need to set up an equation to convert between moles amounts.
This can be done by looking at the coefficients in the chemical equation. So, in this chemical reaction, it tells us for every 3 moles of CuO there is 1 moles of N2.
With this we can write a conversion equation as follows.
[tex]1.96*\frac{1}{3} = .653[/tex]
*Note: in conversion equations the denominator should match the units and or element being multiplied by the other fraction in the numerator. Such as in this instance the 1.96 moles of CuO and 3 moles of CuO are the same.
So, the amount of moles of N2 that can be made when 156.1 grams of CuO are consumed is .653 moles.
Answer:
0.7 mole N₂
Explanation:
To find the amount of N₂ produced, you need to (1) convert grams CuO to moles CuO (via the molar mass) and then (2) convert moles CuO to moles N₂ (via mole-to-mole ratio from reaction coefficients).
The molar mass is the sum of the element molar masses times their quantities. The ratios/conversions should be arranged in a way that allows for the cancellation of units (desired unit in the numerator).
Molar Mass (CuO): 63.5 g/mol + 16 g/mol
Molar Mass (CuO): 79.5 g/mol
2 NH₃ + 3 CuO ----> 3 Cu + 1 N₂ + 3 H₂O
^ ^
156.1 g CuO 1 mole 1 mole N₂
------------------- x ----------------- x ---------------------- = 0.7 mole N₂
79.5 g 3 moles CuO
Boyle's law only works when a gas is kept at a constant temperature. Experimentally this is very tricky as changes in pressure or volume often affect the temperature of a gas. In a real closed piston, rapidly reducing the volume of a gas will actually increase its temperature. Where is the heat that creates this temperature change coming from?
The heat that creates this temperature change coming from change in the internal energy of the system as per as first law of thermodynamics.
What is Boyle's law ?A law stating that the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature.
As we know, Boyle's law only works when the gas is kept at a constant temperature
Here,
When volume of gases decreased, it means work done has occurred on the system, so the work done is used for raising internal energy of the gas and the other is released as the thermal energy.
So,
According to 1st law of thermodynamics,
we know Q = ΔU + W i.e, change in internal energy and work done. So this is a reason. Changing temperature occurs.
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Calculate the pH of a solution that is 0.113 M HCI.
Simplified concentration
[tex]\\ \rm\Rrightarrow 1.13\times 10^{-2}M[/tex]
Now
[tex]\\ \rm\Rrightarrow pH=-log[H^+][/tex]
[tex]\\ \rm\Rrightarrow pH=-log(1.13\times 10^{-2})[/tex]
[tex]\\ \rm\Rrightarrow pH=-log1.13-log10^{-2}[/tex]
[tex]\\ \rm\Rrightarrow pH=-0.05+2[/tex]
[tex]\\ \rm\Rrightarrow pH=1.95[/tex]
Highly acidic
A team of scientists altered the DNA of E. coli bacteria. The bacteria thus developed had the ability to generate insulin exactly identical to the human insulin molecule. What could be the likely impact of this biotechnology on the individual and the society?
The medical costs for insulin-dependent patients would rise.
Large-scale insulin could be produced in relatively lesser time.
The price of insulin available from sources other than bacteria may fall.
The patients who take insulin may become infected with E. coli bacteria.
Answer:
Large-scale insulin could be produced in relatively lesser time.
Explanation:
We already sort of do this where we infect the bacteria with a plasmid containing our insulin gene and it causes them to produce insulin. Since the question is saying that we edited their DNA directly, now these bacteria don't need to be infected with plasmid b/c now they can just pass these genes onto their offspring.
This will allow us to make TONS of insulin cuz bacteria are crazy good at making stuff and growing.
A hot-air balloon has a pressure of 0.715 atm while the temperature outside is 200C. What will the pressure be if the temperature drops to 5C while the volume remains constant?
1.12 kPa
11.2 atm
1203 atm
1.12 atm
The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).
From the question given above, the following data were obtained :
Initial pressure (P₁) = 0.715 atmInitial temperature (T₁) = 200 °CFinal temperature (T₂) = 195 °CVolume = constantFinal pressure (P₂) = ?Now, Let's convert celsius temperature to Kelvin temperature ;
T(K) = T(°C) + 273
Initial temperature (T₁) = 200 °C = 200 °C + 273 = 473 KFinal temperature (T₂) = 195 °C = 195 °C + 273 = 462 KNow, we shall can determine the final pressure (P₂) ;
Initial pressure (P₁) = 0.715 atmInitial temperature (T₁) = 473 KFinal temperature (T₂) = 462 KFinal pressure (P₂) = ?P₁ / T₁ = P₂ / T₂
0.715 / 473 = P₂ / 462
473 × P₂ = 0.715 × 462
P₂ = 0.69 atm
Thus, the final pressure of the hot air balloon is 0.69 atm
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Which of the following statements would correct one of the roles listed in the table?
O Glucose combines with water to form carbon dioxide,
OGlucose reacts with carbon dioxide during photosynthesis.
OOxygen is formed along with glucose during photosynthesis.
O Chlorophyll stores chemical energy needed for photosynthesis.
Answer:
a
Explanation:
glucose combined with water to form carbon dioxide
Answer:
Option C
Explanation:
Because during photosynthesis the reaction is as per following
CO_2+H_2O—»C_2H_12O_6+O_2Clearly
Glucose nd oxygen are formed
Question 4
2 pts
2 NH3 + 3 CuO g 3 Cu + N₂ + 3 H₂O
In the above equation how many moles of water can be made when 14 moles of NH3 are
consumed?
Answer:
9.33
Explanation:
balanced chemical equation:
2NH₃ + 3CuO → 3Cu + N₂ + 3H₂O
14 moles of NH3
2NH₃ → 3H₂O
14 * 2/3 = 9.33
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7. Name the representative particle (atom, molecule, ion or formula unit) of Radon
Answer: A representative particle can be an atom, and an ion. a molecule, or a formula unit.
Explanation:
A representative particle is the smallest unit in which a substance naturally exists. For the majority of elements, the representative particle is the atom. Iron, carbon, and helium consist of iron atoms, carbon atoms, and helium atom, respectively.
Radon is a naturally occurring radioactive gas that is odorless and tasteless.
Atoms-the smallest particle of an element
Ions-atoms with positive or negative charges.
Molecules- two or more covalently bonded atoms.
Formula units- the simplest ratio of ions that make up an ionic compound.
1. Write the reaction rate expressions for the following reactions in terms of the disappearance of the reactants and the appearance of products: 1-(aq)+ OCI-(aq)-CI-(aq)+OI-(aq)
In terms of the disappearance of the reactants, the rate equations are R= -kd[I-]/dt and -kd[OCl-]/dt.
What is an ionic reaction?The term ionic reaction refers to the reaction that takes place between two ions. In this case, the ionic reaction is; I-(aq) + OCl-(aq) -------> Cl-(aq) + OI-(aq).
The rate equations in terms of the disappearance of the reactants is;
R= -kd[I-]/dt
And
R = -kd[OCl-]/dt
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Tobias notices that a particular kind of flower comes in many slightly different shades of pink. In other places, the same flower may be many shades of purple or even blue. He knows that some flowers' colors depend on where they are planted, while others' are determined by their breed. He hypothesizes that the different colors of these flowers are genetically different. Which of the following experimental setups is best for testing this hypothesis?
A hypothesis is a tentative explanation that is put forward for an observation.
What is a hypothesis?A hypothesis is a tentative explanation that is put forward for an observation. In this case, we have to determine whether the location or the kind of breed affects the color of the flowers.
To test the hypothesis, various shades of colors of the flower may be planted on different locations and the growth of each of the shades monitored to ascertain whether the color depends on the location or solely on the kind of breed.
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7.71 Classify each of the following as exothermic or endothermic:
a. CHÂ(g) + 2O₂(g) —^> CO₂(g) + 2H₂O(g) + 802 kJ
b. Ca(OH)₂(s) + 65.3 kJ →→→ CaO(s) + H₂O(l)
c. 2Al(s) + Fe₂O3(s) — Al₂O3(s) + 2Fe(s) + 850 kJ
A. Heat is released, so the reaction is exothermic.
B. Heat is absorbed, so the reaction is endothermic.
C. Heat is released, so the reaction is exothermic.
S + 6 HNO3 →→ H₂SO4 +6 NO₂ + 2 H₂O
->
In the above equation, how many grams of water can be made when 19.7 moles of HNO3 are
consumed?
Round your answer to the nearest tenth. If you answer is a whole number like 4, report
the answer as 4.0
Use the following molar masses. If you do not use these masses, the computer will mark
your answer incorrect.:
Element
Molar
Mass
Hydrogen 1
Nitrogen 14
Sulfur
32
Oxygen 16
12
6.67 x 10-3 g of arsenic (As) is found in a 0.600 L sample of water. If the density of this
sample is 1.00 g/mL, what is the concentration of arsenic in ppm?
ppm = mg/L = mg/kg
6.67 x 10⁻³ g = 6.67 mg
ppm = 6.67 mg : 0.6 L = 11.12
which of the following best describes what happens during nuclear fusion
Answer:
Nuclear fusion is a kind of nuclear reaction in which two lighter nuclei combine under suitable conditions to form heavier nuclei under suitable conditions. A lot of energy is released in this process.
0.160g of Mg is equal to how many moles Mg
The 0.160 grams of Mg is equal to 0.00658 moles of Magnesium (Mg).
Given,
Mass of Mg, m=0.160g
The atomic mass of Mg is 24.31 g.
The number of moles can be represented as the ratio of the given mass of the atom/molecule to the Atomic/Molar mass of the atom/molecule.
Atomic mass can be defined as the mass of the one mole of an atom and Similarily, molecular mass can be defined as the mass of one mole of a molecule.
Number of moles, n=Given mass/Molar mass
n=0.160g/(24.31g/mol)=0.00658 moles
Hence, the 0.160 grams of Magnesium (Mg) is equal to 0.00658 moles of Magnesium (Mg).
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What can help engineers develop ways to prevent rusting?
OA. Understanding the solubility of metal ions
B. Understanding double-displacement reactions
C. Understanding oxidation-reduction reactions
D. Understanding the phase changes of metals
Answer: Understanding oxidation-reduction reactions
Explanation:
Rusting occurs when electrons are exchanged between iron and oxygen.
What happens as a result of the photoelectric effect? A.light is produced
Answer:
photoelectric effect, phenomenon in which electrically charged particles are released from or within a material when it absorbs electromagnetic radiation. The effect is often defined as the ejection of electrons from a metal plate when light falls on it.
If an element has 11 protons and 12 neutrons and 11 electrons, what is the atomic mass of the element?
The atomic mass of the unknown element is; 23
How to find the atomic mass of an element?We are given that;
Number of protons = 11
Number of Neutrons = 12
Number of Electrons = 11
Now, formula for atomic mass is;
Atomic mass = Number of Neutrons + Number of Electrons
Atomic Mass = 12 + 11
Atomic Mass = 23
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A sample of 0.0084 mol of HCl is dissolved in water to make a 1500 mL solution. Calculate the molarity of the HCl solution, the [H3O+] and the pH. For a strong acid such as HCl, the [H3O+] is the same as the molarity of the HCl solution.
A solution prepared by dissolving 0.0084 moles of HCl in 1500 mL of solution has a Molarity of HCl of 5.6 × 10⁻³ M, a Molarity of H₃O⁺ of 5.6 × 10⁻³ M and a pH of 2.3.
What is Molarity ?Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per liters of a solution. Molarity is also known as the molar concentration of a solutionA solution is prepared by dissolving 0.0084 moles of HCl in 1500 mL of solution. The molarity of HCl is:
[HCl] = 0.0084 moles / 1.5 L
= 5.6 × 10⁻³ M
HCl is a strong acid according to the following equation.
HCl(aq) + H₂O(l) ⇒ Cl⁻(aq) + H₃O⁺(aq)
Thus, the concentration of H₃O⁺ will be equal to the initial concentration of HCl, 5.6 × 10⁻³ M.
Now, we will calculate the pH of the solution using its Formula ;
pH = - log[H₃O⁺]
= - log [5.6 × 10⁻³]
= 2.3
Hence, A solution prepared by dissolving 0.0084 moles of HCl in 1500 mL of solution has a Molarity of HCl of 5.6 × 10⁻³ M, a Molarity of H₃O⁺ of 5.6 × 10⁻³ M and a pH of 2.3.
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Please help. I’m confused on where to even start
Answer:
b
Explanation:
because it freezer in temperature
Fill in the blank with the correct number to balance the equation: 4AI +____O2 → 2Al₂O3.
(Enter only a whole number.)
Answer: 3 O2
Explanation:
4AI +____O2 → 2Al₂O3.
In the product, Al and O3 are one chemical now and therefore BOTH impacted by the coeffcient in front of the Al which is 2. We know the coefficient is 2 and there are 3 molecules of O meaning that there are 6 molecules of O in the product. To balance this, there should be 6 molecules of O on the reactant side, the same way there is 4 Al molecules on both sides of the reaction. So 6 divided by 2 is 3 so put a 3 in the blank.
When 50.5 g iron(III) oxide reacts with carbon monoxide, 32.2 g iron is produced. What is the percent yield of the reaction?
Fe2O3(s)+3CO(g)→2Fe(s)+3CO2(g)
93.80 % is the per cent yield of the reaction [tex]Fe_2O_3(s)+3CO(g)[/tex] → [tex]2Fe(s)+3CO_2(g)[/tex].
What is a mole?A mole is a very important unit of measurement that chemists use. A mole of something means you have 602,214,076,000,000,000,000,000 of that thing, like how having a dozen eggs means you have twelve eggs.
[tex]Fe_2O_3(s)+3CO(g)[/tex] → [tex]2Fe(s)+3CO_2(g)[/tex]
[tex]50.5 g Fe_2O_3[/tex] x ([tex]1 mol of Fe_2O_3[/tex] ÷ [tex]159.69 g Fe_2O_3[/tex]) x ([tex]2 mol\; of Fe[/tex] ÷ [tex]1 mol Fe 34.97 g Fe[/tex])
[tex]% of yield = \frac{Practical X 100}{Theoretical}[/tex][tex]Percentage \;of \;yield = \frac{Practical X 100}{Theoretical}[/tex]
[tex]Percentage\; of yield = \frac{32.8 X 100}{34.97}[/tex]
= 93.80 %
Hence, 93.80 % is the per cent yield of the reaction.
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Classify each of the following substances as a compound or element.
a. Gold _____________
b. Ethanol _____________
c. Sugar _____________
d. Sulfur _____________
e. Hydrogen gas______
f. Carbon dioxide_______
Answer:
A. Element
B. Compound
C. Compound
D. Element
E. Compound
F. Compound
Explanation:
Elements are what is already on the periodic table and compounds are the substances created when they are combined.
what makes PLA hydrophilic?
Which statement describes an electron?
O It has a positive charge and is located in the nucleus.
OIt has a positive charge and is located in orbitals around the nucleus.
O It has a negative charge and is located in the nucleus.
O
It has a negative charge and is located in orbitals around the nucleus.
Answer:
D.) It has a negative charge and is located in orbitals around the nucleus.
Explanation:
Electrons always have a negative charge. Since electrons can be shared or donated/received, they must be located in the orbitals around the nucleus. Protons, which have a positive charge, and neutrons, which are neutral, are located in the nucleus.
PLEASE HELP ASAP!!!!!!!!!!!!!!!
Answer:
A and B
Explanation:
A is crust
B is mantle
