Answer:
Option e.
Acid oxalate / oxalate
Explanation:
To determine the most efecttive buffer, we must look the pKas of the system.
If pKa value is similiar to buffer's pH, the variation of pH by the addition of a small amount of strong acid or base is minimal. It would be a good buffer.
a. H₃PO₄ / H₂PO₄⁻ Ka 1 = 6.9×10⁻³
pKa = - log Ka → - log 6.9×10⁻³ = 2.16
b. H₂CO₃ / HCO₃⁻ Ka1 = 4.8×10⁻⁷
pKa = - log Ka → - log 4.8×10⁻⁷ = 6.32
c. HCO₃⁻ / CO₃⁻² Ka2 = 4.8×10⁻¹¹
pKa = - log Ka → - log 4.8×10⁻¹¹ = 10.32
d. H₂S / HS⁻ Ka1 = 8.9×10⁻⁸
pKa = - log Ka → - log 8.9×10⁻⁸ = 7.05
e. HC₂O₄⁻ / C₂O₄⁻² Ka2 = 5.1×10⁻⁵
pKa = - log Ka → - log 5.1×10⁻⁵ = 4.29
pKa which is so close to the ph's value is e, acid oxalate / oxalate
A(n) _______________ can be formed by linking together several monosaccharides via glycosidic bonds.
Answer:
A polysaccharide (n) can be formed by linking several monosaccharides through glycosidic linkages.
Explanation:
Polysaccharides are carbohydrates or complex carbohydrates, where monosaccharides join with glucosidic bonds to form a more complex structure that would be the polysaccharide.
An example of a polysaccharide is starch, or glycogen.
Starch is found in many foods such as potatoes or rice, and glycogen is a form of energy reserve of our organism housed in muscles and liver to fulfill locomotion, physical activity, and other activities that consist of glycolysis.
Polysaccharides are degraded in our body by different stages, and several enzymes unlike monosoccharides or disaccharides, since they have more unions and a more complex structure to disarm in our body and thus assimilate it.
Polysaccharides are also part of animal structures, such as insect shells or nutritional sources, among others.
A particular brand of gasoline has a density of 0.737 g/mL at 25 ∘C. How many grams of this gasoline would fill a 13.6 gal tank (1US gal=3.78L)? Express your answer to three significant figures and include the appropriate units.
Answer:
Mass, m = 37900 grams
Explanation:
Given that,
The density of a brand of gasoline is 0.737 g/mL at 25°C
We need to find mass of gasoline would fill a 13.6 gal tank.
Density is defined as mass per unit volume.
We know that, 1US gal=3.78L
So,
1US gal = 3785.41 mL
13.6 US gal = 51481.6 mL
So,
[tex]d=\dfrac{m}{V}\\\\m=d\times V\\\\m=0.737\ g/mL\times 51481.6\ mL\\\\m=37941.93\ g[/tex]
or
m = 37900 g (in three significant figures)
So, the mass of the gasoline is 37900 grams.
Mass, m = 37900 grams
Given that,
The density of a brand of gasoline is 0.737 g/mL at 25°C
find the mass of gasoline would fill a 13.6 gal tank.
Density is defined as mass per unit volume.
We know that, 1US gal=3.78L
So,
1US gal = 3785.41 mL
13.6 US gal = 51481.6 mL
So,
[tex]Density=\frac{mass}{volume}\\\\0.737\ g/mL=mass/51481.6\ mL\\mass=37941.9392\ g[/tex]
or
m = 37900 g (in three significant figures)
So, the mass of the gasoline is 37900 grams.
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Calculate the percent ionization of 1.60 M aqueous acetic acid solution. For acetic acid, Ka=1.8×10−5.
Answer:0.3348%
Explanation:
Water found in streams, depressions,and from the ground must first bepurified since all water sources should be considered as being contaminated. Which of the followingis not an acceptable method for water purification?a. Adding 2 drops of iodine or bleach toa quart of waterb. Use a commercially produced charcoalfilterc. Boiling the water for 2 minutesd. Filtering the water through a tight-mesh cloth
Answer:
Use a commercially produced charcoalfilter
Explanation:
Water found in streams, depressions and ground water must be contaminated with pathogenic microorganisms. The methods of disinfection using iodine or bleach or boiling the water for about two minutes and then filtering it with a clean cloth will effectively remove the microorganisms.
However, charcoal filters do not eliminate microorganisms from water hence this method is not acceptable in this case.
what is scientific method
Answer:
a method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.
Explanation:
a method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.
Afarmer applies 1705 kg of a fertilizer that contains 10.0% nitrogen to his fields each year. Fifteen percent (15.0%) of the fertilizer washes into a river
that runs through the farm.
5th attempt
Il See Periodic Table See Hint
If the river flows at an average rate of 0.455 cubic feet per second, what is the additional concentration of nitrogen (expressed in
milligrams of nitrogen per liter) in the river water due to the farmer's fertilizer each year?
mg/L
Answer:
The additional concentration of nitrogen in the river water due to the farmer's fertilizer is 0.0629 milligrams per liter
Explanation:
The mass of the fertilizer the farmer applies = 1705 kg
The percentage of nitrogen contained in the fertilizer = 10%
Therefore;
The mass of nitrogen contained in the fertilizer = 10% of 1705 kg = 10/100 × 1705 kg
The mass of nitrogen contained in the fertilizer = 10/100 × 1705 kg = 170.5 kg
The percentage of the fertilizer that washes into the river that runs through the farm = 15.0%
The mass of the fertilizer that washes into the river = 15/100 × 170.5 = 25.575 kg = 25575 g = 25575000 mg
The volume of water that flows through the farm = 0.455 cubic feet per second
The volume of water that flows through the farm in a year = 0.455 ft³ × 60 × 60 × 24 × 365 = 14348880 ft³ = 406,315.03 m³ = 406,315,034 l
The number of moles of nitrogen = Mass of nitrogen/(Molar mass of nitrogen)
Molar mass of nitrogen =14.0067 g/mol
Therefore;
The number of moles of nitrogen = 25575 kg/(14.0067 g/mol) = 1.825.912 moles
The additional concentration of the nitrogen in moles = 1.825.912 moles/(406,315,034 l) = 4.49 × 10⁻⁶ mol/liter
The additional concentration of the nitrogen in milligrams of nitrogen per liter of water = 25575000/406,315,034 = 0.0629 milligrams of nitrogen per liter.
Therefore, the additional concentration of nitrogen in the river water due to the farmer's fertilizer = 0.0629 milligrams per liter
The rate constant for a reaction is 4.65 L mol-1s-1. What is the overall order of the reaction? zero
Answer:
second order
Explanation:
units of reaction and their order.
Zero order --> M^1 s^-1 = M/s
First order --> M^0 s^-1 = 1/s
Second order --> M^-1 s^-1 = L/mol s
In the question rate constant k = 4.65 L mol-1s-1. = 4.65 L/mol s
Hence, the reaction is a second order reaction
Answer:
The answer is "second".
Explanation:
Given:
rate constant for a reaction = 4.65 [tex]\frac{L}{mol \cdot s}[/tex]
[tex]\text{The rate of unit} = \frac{m}{s} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ _{where} \ \ M=\frac{mol}{l} \\\\[/tex]
[tex]=\frac{mol}{l \cdot s}[/tex]
The orders unit value of the k
0 [tex]\frac{m}{s}[/tex]
1 [tex]\frac{1}{s}[/tex]
2 [tex]\frac{l}{m s}[/tex]
The rate of the unit is constant for the second-order that's why it is correct.
who can help me think of a good observation then a hypothesis thanks!
a cylinder is filled with air its radius is 6.00 cm and its height is 3.50 cm what is the volume of air
Answer:
395.84cm^3
Explanation:
volume of a cylinder:
V=π(r^2)h
V = π((6cm)^2)(3.50cm) = 395.84cm^3
is ethyl ether a polar molecule
Answer:
Ethyl ethers are Non-polar solvent and can extract polar molecules such as fatty acids
Butanoic acid, HC4H7O2, has a pKa value = 4.82. What is the value of the ionization constant for butanoic acid?
Answer:
1.51 × 10⁻⁵
Explanation:
Step 1: Given data
pKa value: 4.82
Step 2: Write the reaction for the acid ionization of butanoic acid, HC₄H₇O₂
Butanoic acid is a weak acid that ionizes according to the following equation.
HC₄H₇O₂(aq) ⇄ C₄H₇O₂⁻(aq) + H⁺(aq)
The acid ionization constant for this reaction is Ka
Step 3: Calculate the value of the ionization constant for butanoic acid
We will use the following expression.
pKa = -log Ka
Ka = antilog -pKa = antilog -4.82 = 1.51 × 10⁻⁵
PLEASE HELP URGENT
>
Convert a speed of 857 mi/h to units of feet per minute. Also, show the unit analysis by dragging components into the
unit-factor slots.
Answer Bank
857 mi
Х
ih
()*(
60 min
12 in
1 min
1 mi
1 ft
5280 ft
3 ft
60 s
1h
60 h
857 mi/h =
ft
min
Answer:
75416 ft/min
(857 mi/h) x (5280 ft/h ÷ 1 mi / 1h ) x (1h x 1 ft ÷ 60 min x 1 ft)
Explanation:
Conversion of 857 mi/h to feet /second.
We'll begin by converting 857 mi/h to ft/h.
This is illustrated below:
Recall:
1 mi/h = 5280 ft/h
Therefore,
857 mi/h = 857 x 5280 = 4524960 ft/h
857 mi/h = 4524960 ft/h
Finally, we shall convert 4524960 ft/h to ft/min.
This can be obtained as follow:
Recall:
1 ft/h = 1/60 ft/min
Therefore,
4524960 ft/h = 4524960 x 1/60 = 75416 ft/min
4524960 ft/h = 75416 ft/min
Therefore, 857 mi/h is equivalent to 75416 ft/min.
To solve the above question in a shorter for we simply do the following:
(857 mi/h) x (5280 ft/h ÷ 1 mi/1h ) x (1h x 1 ft ÷ 60 min x 1 ft)
Question 3 of 10
In order to test a hypothesis, a scientist needs to:
A. perform an experiment.
B. summarize previously recorded data.
c. have other scientists agree with the hypothesis.
D. develop an educated guess.
Answer:
A- Perform an experiment
Explanation:
convert 3427 into scientific notation
Answer:
[tex]3.427 \times {10}^{3} [/tex]
what is colloidal solutions
Explanation:
Colloidal solutions, or colloidal suspensions, are nothing but a mixture in which the substances are regularly suspended in a fluid. ... Colloidal systems can occur in any of the three key states of matter gas, liquid or solid. However, a colloidal solution usually refers to a liquid concoction.
Answer:
Colloidal solutions, or colloidal suspensions, are nothing but a mixture in which the substances are regularly suspended in a fluid.
Consider the molecule 1-tert-butyl-3-methylcyclohexane. These two groups can be cis or trans. Which arrangement is more stable
Answer:
Cis configuration is more stable
Explanation:
Generally the is configuration of cycloalkenes is more thermo-chemically stable than the trans-configuration double bonds, because the latter causes twists in the ring, resulting in higher strain.
This also mean that there is a greater force of repulsion between cis molecules (little r no twists).
I hope you find this explanation was clear and helpful.
Calculate the pH after the addition of 10.0 mL of 0.240 M sodium hydroxide to 50.0 mL of 0.120 M acetic acid.
Answer:
pH = 4.58
Explanation:
The reaction of NaOH with acetic acid, CH₃COOH occurs as follows:
NaOH + CH₃COOH → CH₃COO⁻Na⁺ + H₂O
Moles that react:
NaOH = 10mL = 0.010L * (0,240mol / L) = 0.0024 moles NaOH
CH₃COOH = 50.0mL = 0.050L * (0.120mol / L) = 0.0060 moles CH₃COOH
That means after the reaction you will have:
CH₃COOH: 0.0060 mol - 0.0024 mol = 0.0036 moles
CH₃COO⁻Na⁺: 0.0024 moles
in solution, you will have the mixture of a weak acid (Acetic acid), with its conjugate base (sodium acetate, CH₃COO⁻Na⁺). And pH of this buffer can be determined using H-H equation:
pH = pKa + log [A⁻] / [HA]
For Acetic buffer pKa = 4.76:
pH = 4.76 + log [CH₃COO⁻Na⁺] / [CH₃COOH]
Where [] is molarity of each species or moles
Replacing:
pH = 4.76 + log [0.0024 moles] / [0.0036 moles]
pH = 4.58
Which four of the following statements about amino acids are true?
(a) Proline has an overall charge at physiological
pH(7.4).
(b) Thr and Ser are polar amino acids.
(c) Lysine has one stereocenter (chiral center).
(d) The form of glycine used by the human body is D -glycine.
(e) The Ala side chain does not form hydrogen bonds with other amino acids.
(f) Methionine is a thiol.
(g) Phe can undergo oxidation to form Tyr.
Answer: • Phe can undergo oxidation to form Tyr.
• The Ala side chain does not form hydrogen bonds with other amino acids.
• Thr and Ser are polar amino acids.
• Lysine has one stereocenter (chiral center).
Explanation:
Amino acids are simply organic compounds which are known to contain carboxyl and amine functional groups and the main elements that are found in an amino acid are oxygen, carbon, hydrogen, and nitrogen.
The true statements about amino acids are:
• Phe can undergo oxidation to form Tyr.
• The Ala side chain does not form hydrogen bonds with other amino acids.
• Thr and Ser are polar amino acids.
• Lysine has one stereocenter (chiral center).
It should be noted that Methionine is not a thiol but rather a thio ether. Also, proline is simply a neutral amino acid and the statement that proline has an overall charge at physiological
pH(7.4) is false.
Predict the formula for a compound made from X3+ and Y− .
Answer:
XY₃
Explanation:
We have cations of the X³⁺ type and anions of the Y⁻ type. For a compound to be formed, it has to be electrically neutral, that is, it must have the same number of positive charges and negative charges so that the final charge of the compound is zero. In this case, the compound would be neutral if it had 1 atom of X³⁺ and 3 atoms of Y⁻. The resulting chemical formula would be XY₃.
g Given that 50.0 mL of 0.100 M magnesium bromide reacts with 13.9 mL of silver nitrate solution according to the unbalanced equation MgBr21aq2 AgNO31aq2 S AgBr1s2 Mg1NO3221aq2 (a) What is the molarity of the AgNO3 solution
Answer:
0.719M AgNO₃
Explanation:
The balanced chemical equation is:
MgBr₂ + 2AgNO₃ ⇄ 2AgBr + Mg(NO₃)₂
Where 1 mole of magnesium bromide reacts completely with 2 moles of AgNO₃
Molarity is the ratio between moles of solution and its volume in liters (The volume of the solution is 13.9mL = 0.0139L). That means all we need is to determine moles of silver nitrate. It is possible to know by using the chemical equation, thus:
Moles AgNO₃:
Moles of MgBr₂:
50.0mL = 0.050L * (0.100mol / L) = 0.00500 moles of MgBr₂.
As 2 moles of AgNO₃ reacts per mole of MgBr₂ and the reaction occurs completely, moles of silver nitrate are:
0.00500 moles MgBr₂ * (2 moles AgNO₃ / 1 mole MgBr₂) =
0.0100 moles of AgNO₃ are in the solution.
And molarity is:
0.0100 moles AgNO₃ / 0.0139L =
0.719M AgNO₃A sample of 2.00 mol of gas in a 10.00 L container is at 45.0 °C. What is the pressure (in atm) of the gas?
Answer:
5.22 atm
Explanation:
The following data were obtained from the question:
Number of mole (n) = 2 moles
Volume (V) = 10 L
Temperature (T) = 45 °C
Pressure (P) =?
Next, we shall convert 45 °C to Kelvin temperature. This can be obtained as follow:
Temperature (K) = Temperature (°C) + 273
T (K) = T (°C) + 273
T (°C) = 45 °C
T(K) = 45 °C + 273
T (K) = 318 K
Finally, we shall determine the pressure of the gas by using the ideal gas equation as shown below:
Number of mole (n) = 2 moles
Volume (V) = 10 L
Temperature (T) = 318 K
Gas constant (R) = 0.0821 atm.L/Kmol
Pressure (P) =.?
PV = nRT
P x 10 = 2 x 0.0821 x 318
Divide both side by 10
P = (2 x 0.0821 x 318) /10
P = 5.22 atm
Therefore, the pressure of the gas is 5.22 atm
The liquid 2-chloro-2,3-dimethylbutane has a density of 0.878 g/mL at 20.0°C. If a 138 gram sample of this compound is needed, what volume of the liquid at 20.0°C must be provided? volume= mL
Answer:
157 mL
Explanation:
Step 1: Given data for 2-chloro-2,3-dimethylbutane
Density (ρ): 0.878 g/mL
Mass (m): 138 g
Volume (V): ?
Step 2: Calculate the volume of the liquid required
The density of a compound is equal to its mass divided by its volume. We will use the following expression.
ρ = m / V
V = m / ρ
V = 138 g / (0.878 g/mL)
V = 157 mL
Which of these is the best hypothesis for why your tire's air pressure is low? If the pressure in the tire is low, then the tire lost air pressure because air is escaping through a hole in the tire. If the pressure in the tire is low, then someone let air out of the tire, because tires do not lose air naturally.
Answer:
If the pressure in the tire is low, then the tire lost air pressure because air is escaping through a hole in the tire.
Explanation:
The tire will lose air from a puncture in the tire, rather than the the second hypothesis saying tires do not lose air naturally.
Answer:
1) If the pressure in the tire is low, then the tire lost air pressure because air is escaping through a hole in the tire
Explanation:
I JUST DID IT
Calculate the mass of a substance with a density of 1.98 g/mL and a volume of 265 mL.
Answer:
mass = 524.7 gExplanation:
The density of a substance can be found by using the formula
[tex]Density = \frac{mass}{volume} [/tex]
Making mass the subject we have
mass = Density × volumeFrom the question
Density = 1.98 g/mL
volume = 265 mL
Substitute the values into the above formula and solve for the mass
That's
mass = 1.98 × 265
We have the final answer as
mass = 524.7 gHope this helps you
When was the first record of a scientific method being used?
Answer:
In the mid-19th century Claude Bernard was also influential, especially in bringing the scientific method to medicine. In his discourse on scientific method, An Introduction to the Study of Experimental Medicine (1865), he described what makes a scientific theory good and what makes a scientist a true discoverer.
Explanation:
(3.434)(1.245)\43.234
Answer:
0.09889
Explanation:
Order of Operations: BPEMDAS
Sig figs: 4
Step 1: Write out equation
[tex]\frac{3.434(1.245)}{43.234}[/tex]
Step 2: Multiply
[tex]\frac{4.27533}{43.234}[/tex]
Step 3: Divide
0.098888
Step 4: Round
0.09889
Quinine C20H24N2O2, is a compound extracted from cinchona tree which is traditionally
used to treat malaria. If given a 1.08 g of quinine sample, calculate:
(a)the molecular mass of quinine.
(b)number of moles of quinine
Answer:
324.46 amu
3.33 × 10⁻³ mol
Explanation:
(a) Calculate the molecular mass of quinine, C₂₀H₂₄N₂O₂
We will add the mass of each atom times the number of each atom in a molecule.
20 × C + 24 × H + 2 × N + 2 × O
20 × 12.01 amu + 24 × 1.01 amu + 2 × 14.01 amu + 2 × 16.00 amu
324.46 amu
(b) Calculate the number of moles of quinine in 1.08 g of quinine
The molar mass of quinine is 324.46 g/mol.
1.08 g × (1 mol/324.46 g) = 3.33 × 10⁻³ mol
An intramuscular medication is given at 20 mg/kg of body weight. If you give 560 mg of medication to a patient, what is the patient’s weight in pounds? (1 kg = 2.20 lbs)
Answer:
62 lb
Explanation:
Step 1: Given data
Dosage of the intramuscular medication: 20 mg/kg of body weight
Mass of the intramuscular medication: 560 mg
Step 2: Calculate the body weight of the patient
560 mg IM × (1 kg BW/20 mg IM) = 28 kg BW
Step 3: Convert the body weight of the patient to pounds
We will use the relationship 1 kg = 2.20 lb.
28 kg × (2.20 lb/1 kg) = 62 lb
Use Hess's Law to calculate the enthalpy change for the reaction
WO3(s) + 3H2(g) => W(s) + 3H2O(g)
from the following equations:
2W(s) + 3O2(g) => 2WO3(s) DH = -1685.4 kJ
2H2(g) + O2(g) => 2H2O(g) DH = -477.84 kJ
Answer:
ΔH = 125.94kJ
Explanation:
It is possible to make algebraic sum of reactions to obtain ΔH of reactions (Hess's law). In the problem:
1. 2W(s) + 3O2(g) → 2WO3(s) ΔH = -1685.4 kJ
2. 2H2(g) + O2(g) → 2H2O(g) ΔH = -477.84 kJ
-1/2 (1):
WO3(s) → W(s) + 3/2O2(g) ΔH = 842.7kJ
3/2 (2):
3H2(g) + 3/2O2(g) → 3H2O(g) ΔH = -716.76kJ
The sum of last both reactions:
WO3(s) + 3H2(g) → W(s) + 3H2O(g)
ΔH = 842.7kJ -716.76kJ
ΔH = 125.94kJThe enthalpy change (ΔH) for the reaction is 125.94kJ.
Hess's Law:
The Hess's law states that the total enthalpy change during a complete chemical reaction is the same regardless of the path taken by the chemical reaction.
It is possible to make algebraic sum of reactions to obtain ΔH of reactions (Hess's law).
It is given that:
1. 2W(s) + 3O₂(g) → 2WO₃(s) ΔH = -1685.4 kJ
2. 2H₂(g) + O₂(g) → 2H₂O(g) ΔH = -477.84 kJ
On dividing equation 1. by - 1/2 for simplification we get:
W(s) + 3/2 O₂(g) → WO₃(s) ΔH = 842.7kJ....................(a)
On dividing equation 2. by 3/2 for simplification we get:
3H₂(g) + 3/2O₂(g) → 3H₂O(g) ΔH = -716.76kJ...................(b)
On adding equations (a) and (b)
WO₃(s) + 3H₂(g) → W(s) + 3H₂O(g)
ΔH = 842.7kJ -716.76kJ
ΔH = 125.94kJ
The enthalpy change for the reaction is 125.94 kJ.
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Which of the following is an example of pseudoscience?
a. Finding a new star
b. Predicting your horoscope
C. Dating the age of a fossil
d. Finding new uses for drug
Answer:
b. Predicting your horoscope
Explanation:
Pseudoscience refers to claims that are scientifically misleading and do not follow the scientific method. For example, imagine someone claims a certain drug will make you live forever. This is an example of pseudoscience. It has not been tested using the scientific method and it is misleading.
The scientific method follows this general structure.
1. Ask a question
2. Do background research
3. Construct a hypothesis
4. Test your hypothesis
5. Analyze data and draw a conclusion
6. Communicate your results. (Was your hypothesis correct?)
Finding a new star, dating the age of a fossil, and finding new uses for a drug all are processes that use the scientific method. Predicting your horoscope is not a science and it has not been proven using the scientific method.
An example of pseudoscience is " predicting your horoscope".
What is pseudoscience?The term "pseudoscience" refers to claims that something is both true and scientific but are somehow incompatible well with the scientific process.
What is horoscope?A horoscope would be a representation of the Sun, Moon, planets, astrological aspects, and various critical angles at the time of the occurrence, such as that of the period of a person's birth, using an astrological chart as well as a diagram.
Therefore, An example of pseudoscience is " predicting your horoscope".
Hence, the correct answer will be option (b).
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