Answer:
a. 122.6 mL / pH = 4.03
b. 193.6 mL / pH = 5.73
Explanation:
In the equivalence point we know: mmoles acid = mmoles base- And the pH in a titration between a weak base and a strong base, is acid, at the equivalence point. For the volume, we can replace the equation with the data given.
a. 0.125M . volume of acid = 65.5 mL . 0.234M
Volume of acid = (65.5 . 0.234) / 0.125 = 122.6 mL
Total volume at the equivalence point = 188.1 mL
b. 0.125M . volume of acid = 21.8 mL . 1.11 M
Volume of acid = (21.8 . 1.11) / 0.125 = 193.6 mL
Let's calculate the pH. In the equilavence point we have a neutralization reaction.
a. NH₃ + HCl → NH₄Cl
All the mmoles of protons (65.5 mL . 0.234M) react to ammonia, to obtain ammonium.
New concentration is: 15.32 mmoles / 188.1 mL = 0.0814 M
This is the [NH₄⁺] to determine the pH in the acid base equilibrium.
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺ Ka
Expression for Ka = [NH₃] . [H₃O⁺] / [NH₄⁺]
5.6×10⁻¹⁰ = x² / (15.32 - x)
(We can avoid the quadratic equation 'cause Ka is so small)
√(5.6×10⁻¹⁰ . 15.32) = x → [H₃O⁺] = 9.26×10⁻⁵
pH = - log [H₃O⁺] → 4.03
b. CH₃NH₂ + HCl → CH₃NH₃Cl
All the mmoles of protons (21.8 mL . 1.11M) react to methylamine, to obtain methylammonium.
New concentration is: 24.2 mmoles / 193.6 mL = 0.125 M
This is the [CH₃NH₃⁺] to determine the pH in the acid base equilibrium.
CH₃NH₃⁺ + H₂O ⇄ CH₃NH₂ + H₃O⁺ Ka
Expression for Ka = [CH₃NH₂] . [H₃O⁺] / [CH₃NH₃⁺]
2.7×10⁻¹¹ = x² / (0.125 - x)
(We can avoid the quadratic equation 'cause Ka is so small)
√(2.7×10⁻¹¹ . 0.125) = x → [H₃O⁺] = 1.84×10⁻⁶
pH = - log [H₃O⁺] → 5.73
The pH of the equivalence point of 0.125M HCl with NH₃ is 4.03 and with CH₃NH₂ is 5.73.
What is equivalence point?In the acid - base titration, at the equivalence point equal moles of acid as well as of base are present.
First we calculate the volume of HCl by using the below equation as:
M₁V₁ = M₂V₂, whereM₁ = molarity of NH₃ = 0.234 M
V₁ = volume of NH₃ = 65.5 mL
M₂ = molarity of HCl = 0.125 M
V₂ = volume of HCl = ?
V₂ = (65.5 . 0.234) / 0.125 = 122.6 mL
Total volume at the equivalence point = 188.1 mL
Chemical reacion will be written as:
NH₃ + HCl → NH₄Cl
All moles of protons react with moles of ammonia, so new moles (n) will be calculated as:
n = molarity × volume
n = 65.5 mL × 0.234M = 15.32 moles
Now, concentration in terms of molarity will be 15.32 mmoles / 188.1 mL = 0.0814 M
pH in the acid-base reaction due to [NH₄⁺], as:
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺
Value of Ka for this reaction is = 5.6×10⁻¹⁰
According to the ICE table, Ka equation will be written as-
5.6×10⁻¹⁰ = x² / (15.32 - x)
x = [H₃O⁺] = 9.26 × 10⁻⁵
pH = - log [H₃O⁺] = 4.03
Again we calculate the volume of HCl with the CH₃NH₂ as:0.125M . volume of acid = 21.8 mL . 1.11 M
Volume of acid = (21.8 . 1.11) / 0.125 = 193.6 mL
Total volume at the equivalence point = 215.4 mL
Chemical reacion will be written as:
CH₃NH₂ + HCl → CH₃NH₃Cl
All moles of protons react with moles of ammonia, so new moles (n) will be calculated as:
n = 21.8 mL . 1.11M = 24.2 moles
Now, concentration in terms of molarity will be 24.2 moles / 215.4 mL = 0.11M
pH in the acid-base reaction due to [CH₃NH₃⁺], as:
CH₃NH₃⁺ + H₂O ⇄ CH₃NH₂ + H₃O⁺
Value of Ka = 2.7×10⁻¹¹
According to the ICE table, Ka equation will be written as-
2.7×10⁻¹¹ = x² / (0.11 - x)
x = [H₃O⁺] = 5.4×10⁻⁶
pH = - log [H₃O⁺] = 5.73
Hence the value of pH will be 4.03 and 5.73 respectively.
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How does the density and distribution of your “stars” change as the balloon expands?
Answer:
The Universe is constantly expanding and as it expands the stars and objects in space move farther apart, just like the points on the balloon when air is blown into it. Density and distribution of "stars" as the balloon expands because when volume increases the density will increase.
Hope this Helps
Explain why atoms in group 2a are likely to form ions with plus two charge explain why why atoms in group 7a are likely to form ions with a minus one charge
Answer:
Atoms in group 2a are likely to form ions with a +2 charge because they have two valence electrons, both of which experience a very weak pull from the nucleus due to electron shielding. This causes the atoms to be easily pulled away from the nucleus, creating the +2 ions we see in nature.
Atoms in group 7a are likely to form ions with a -1 charge because they are one electron away from completing their outermost shell. The large number of protons in the middle of these atoms also causes the valence electrons to experience a stronger net force. This force also pulls strongly on the valence electrons of other atoms, causing the -1 ions we see in nature.
Explain your thoughts on whether or not using solely IR is a good method to make positive IDs of chemicals.
Answer:
No, IR should not soely be used to identify molecules
Explanation:
IR is a method that identifies the functional groups in a molecule by deducing the frequency of stretching and vibration of bonds. Each peculiar type of bond has a frequency for the vibration of each bond represented on the IR spectrum.
However, one method is never enough to identify a compound. A combination of methods must always be used to clear up ambiguities arising from overlapping IR frequencies. Also, interpretation of the nuanced peaks of the fingerprint region in IR spectra is quite challenging and only gives a fair idea of the functional groups present in the compound.
Therefore other methods such as NMR, UV-VISIBLE etc should also be involved in the identification of compounds.
what causes convection currents in a gas or liquid?
Answer:
Convection currents are caused by a temperature difference in gases and liquids. As one area becomes warmer than another the molecules have more energy and start vibrating more vigorously thus spreading out and becoming less dense. This means that the less dense parts will become more buoyant causing them to rise.
Explanation:
Answer:
Convection currents are caused by a temperature difference in gases and liquids.
Explanation:
As one area becomes warmer than another the molecules have more energy and start vibrating more vigorously thus spreading out and becoming less dense. This means that the less dense parts will become more buoyant causing them to rise.
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Question 10 of 12- POS
GR8 Sci U03 USA FY21 Question: 1-10
Hannah added a silvery white metal to a beaker of cold water and noticed that gas bubbles were given off and a different substance formed. When she repeated the activity with hot water she noticed the gas bubbles were
released much more rapidly. Which statement best explains why the reaction occurred faster in hot water?
M
The correct answer is Hot water increases the collision rate of molecules, causing the reaction to occur faster.
Explanation:
Temperature is directly related to the kinetic energy or movement of molecules in a substance. In this context, a higher temperature leads to more kinetic energy or more collision between molecules. At the same time, a chemical reaction involves molecules of two or more substances colliding and creating bonds to form new substances. This implies an increase in temperature means molecules colliding faster, new substances forming in a shorter time, and therefore a faster chemical reaction. According to this, the first answer is correct.
Identify at least 5 pure substance found in nature,in the supermarket, grocery storeand even at your home.use the table below to explain your answer based on appearance, separating technique, boiling and melting point.
Answer:
Explanation:
1) Pure substance: Water (found at home)
Appearance: It is homogeneous since it is a single substance that appears as liquid. Homogeneous is when the components of a substance are in a single phase
Separating technique: It's component cannot be separated by physical means
Boiling point: Water boils at 100 °C
Melting point: Water melts/freezes at 0°C
2) Pure substance: Table salt (found at home)
Appearance: It is also homogeneous as it is a single substance that is solid. Separating technique: It's component cannot be separated by physical means
Boiling point: Water boils at 1,465 °C
Melting point: Water melts/freezes at 801 °C
3) Pure substance: Butter (found at home and grocery store)
Appearance: It is homogeneous even though it contains different components
Separating technique: It's component can be separated by physical means since butter is an emulsion of fat in water. The 15% water content can be evaporated/distilled out at 100 °C
Boiling point: Butter starts boiling at about 110-120 °C
Melting point: It melts at about 37 °C
4) Pure substance: Candle (wax) (found at home and grocery store)
Appearance: It is homogeneous
Separating technique: It's component cannot be separated by physical means
Boiling point: It starts boiling around 370 °C
Melting point: It melts at about 37 °C
5) Pure substance: table sugar/sucrose (found at home, grocery stores and in supermarkets)
Appearance: It is homogeneous
Separating technique: It's component cannot be separated by physical means
Boiling point: It starts boiling around 697 °C
Melting point: It melts at about 186 °C
A pure substance is an homogeneous material, having a composition, and
properties that are consistent through out the material.
The chemical properties of a pure substance are defined, such as the
products of its reaction can be predictable.
A chemical is pure when it consist of a single type of particle such as an
element, a molecule or a compound.
The five pure substances are presented as follows;
[tex]\displaystyle\begin{tabular}{|l|l|l|l|l|}\underline{Pure \ Substances}&\underline{Appearance}&\underline{Separaing Tech}&\underline{Boiling \ Point}&\underline{Melting \ point}\\1. Diamond&Translucent \ solid&Inseparable&3550^{\circ}&4830^{\circ}\\2. Table \ salt&White\ crystals&Insepble&801^{\circ}&1413^{\circ}\\3. Water&Tran parent \ liquid&Insepble&0^{\circ}&100^{\circ}\\4. Sugar&Whilte \ crystals&Heating&Decomposes&186^{\circ}\\5. Gold&Yellowish \ metal&Inseparable& 2700^{\circ}&1064^{\circ}\end{array}[/tex]
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Draw the correct structure(s) for (2R,3S)‑2,3‑dibromobutane. Show stereochemistry clearly. To ensure proper grading, explicitly draw all four groups, including wedge/dash bonds, around a chirality center. Indicate whether the compound(s):_____.a. could exist in an optically active form.b. could exist in optically active form.b. cannot exist in optically active form.c. cannot be determined.
Answer:
b. cannot exist in optically active form
Explanation:
Stereochemistry is a branch of chemistry that involves the spatial arrangement of the atoms of molecules and studies how this affects the physical and chemical properties of such species.
The correct structure for (2R,3S)‑2,3‑dibromobutane can be seen in the image attached below. Since the compound is a meso compound due to the plane of symmetry. Thus, the compound is achiral. i.e. Compounds that are superimposable on its mirror image. The plane of symmetry is vertical inclined at 90°(i.e. perpendicular) to the page thus goes via the middle of the molecule.
an electric current causes water to be transformed into hydrogen and oxygen gasses a physical change or a chemical change
MULTIPLE CHOICE: For a combustion system, incorrect statement is?
Answer:
I THINK it's D, I could be incorrect, however.
Explanation:
C3H8O, as it is flammable, and thus I wouldn't imagine it being a product of combustion. I could be incorrect, so take my answer with a grain of salt.
Cells pump definition
Answer:
Pumps also called transporters, are transmembrane proteins that actively move ions and/or solutes against a concentration or electrochemical gradient across biological membranes.
Which statement best describes why a chemical property change is different from a physical change?
A. A chemical change results in a different state of matter; and a physical change results in a new substance being formed.
B. A chemical change results in a new substance being formed; whereas, a physical change will result in a different state of matter.
C. A chemical change is used by scientists to create new substances, and a physical change happens naturally.
D. A chemical change is used to identify characteristics of a substance, and a physical change identifies the behavior of a substance when in a reaction.
Answer:
B
Explanation:
a chemical change is making a new substance and physical change with a result in a different state of matter:)
An egg sinks in fresh water but it floats on salty water.why?
PLEASE HURRY WILL GIVE BRAINLEST IF ANSWERED CORRECTLY
which separation method would be most successful in separating the components of a homogeneous mixture
screening
evaporation
centrifugation
magnetic separation
Answer:
Evaporation is a technique used to separate out homogeneous mixtures where there is one or more dissolved salts.
Explanation:
Hope this helps :)
2. Enumerate four Reactive Oxygen Species (ROS)
Answer:
Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen.
Sweat is made up of all EXCEPT what?
*
A.Sugar
B.Salt
C.Urea
D.Urine
PLS HELP 35 POINTS I WILL GIVE BRAINEST
Answer:
Just count all the different elements like what elemets are in there and you have to identify the number of elemenst
Explanation:
for example H20 and a chemical for example thats two so you identofy which elelments are in there doesnt matter if thered multiple of it all its asking is what id the number of elemts there meaning like one or 2 mayne six different elements
How much water must be added to 424 mL of 0.189 M HCl to produce a 0.140 M solution?
Answer:
Volume of water added = 148.4 mL
Explanation:
Given data:
Initial volume = 424 mL
Initial molarity = 0.189 M
Final molarity = 0.140 M
Volume of water added = ?
Solution:
Formula:
M₁V₁ = M₂V₂
0.189 M×424 mL = 0.140 M×V₂
V₂ = 0.189 M×424 mL /0.140 M
V₂ = 80.136 M.mL / 0.140 M
V₂ = 572.4 mL
Final volume of solution is 572.4 mL.
Volume of water added = Final volume - initial volume
Volume of water added = 572.4 mL - 424 mL
Volume of water added = 148.4 mL
Which of the following grouping contains only representative elements?
A. Na, Co, S
B. Ni, Ga, Zn
c. AI, Mg, LÍ
D. CI, O, Cd
Answer:
C
Explanation:
Al=Aluminum
Mg=Magnesium
0.1400 mole of sucrose, C12H22O11, contains ________ moles of C.
can you show me the formula and the correct format
Answer:
it has 12 carbon atoms and 22 hydrogen atoms and 11 oxygen atoms
Explanation:
How are changes of state different from chemical change?
Question:
How are changes of state different from chemical change?
Answer:
Physical changes alter only the size, shape, form or matter state of a material. Water boiling, melting ice, tearing paper, freezing water and crushing a can are all examples of physical changes.
On the other hand, chemical changes are a bit different. In a chemical change, a new substance is formed.
Answer:
Chemical change happens when a substance changes they molecular structure, it often involves change in color (rusting iron), transfer of energy (copper smelting), or gas bubbling.
Changes of state is a physical change. An example is ice, it melts to create water. Water then can be freezed back to ice. Water is still H2O in both states（solid/liquid) Dissovling is another example. You can dissolve salt in water and can separate it by evaporating water and leaving the salt behind.
Explanation:
What are the starting substances (molecules) in a chemical equation called?
Answer:
A chemical reaction is the process in which atoms present in the starting substances rearrange to give new chemical combinations present in the substances formed by the reaction. These starting substances of a chemical reaction are called the reactants, and the new substances that result are called the products.
how many moles of ethanol C2H6O, are in a 10.0g sample
Answer: 0.217 mol
Explanation:
To find the amount of moles in a 10 g sample, we need the molar mass of ethanol.
Molar Mass: 46.07 g/mol
Now that we have the molar mass, we can find moles.
[tex]10.0 g*\frac{1mol}{46.07g}=0.217 mol[/tex]
We know that there are 0.217 mol in a 10.0 gram sample.
Match Term Definition
Pure substance A) Liquid homogeneous mixture in which the solute is distributed evenly within the solvent
Heterogeneous B) Mixture that has its different components mixed evenly within the substance
Homogeneous C) Mixture that has its different components mixed unevenly within the substance
Solution D) Consists of a single element or type of compound
Answer:
b
Explanation:
this should help
Convert the speed of light, 3.0 x 10^8 m/s, into mi/hr. (1610 m = 1 mi). Could you please explain step by step thank you!
Answer:
[tex]v=6.7\times 10^9\ mi/hr[/tex]
Explanation:
Given that,
The speed of light is 3×10⁸ m/s
We need to convert it into mi/hr.
Since, 1 mile = 1610 m
1 hour = 3600 s
So,
[tex]v=3\times 10^8\ \dfrac{m}{s}\\\\=3\times 10^8\ \dfrac{\dfrac{1}{1610}\ \text{miles}}{\dfrac{1}{3600}\ s}\\\\=6.7\times 10^9\ mi/hr[/tex]
So, the required speed of light is [tex]6.7\times 10^9\ mi/hr[/tex].
What are phytoplankton and what percentage of oxygen do they produce? (ASAP)
Answer:
They are plants also known as plankton and they produce about 80-85% of the world's oxygen.
Explanation:
At the Sparta Fault in Greece, the hanging wall is below the footwall. This type of fault is called a .
Answer:
1 a
Explanation:
A gas sample in a balloon contains 4.0 moles of gas at a particular pressure, volume and temperature. If your balloon springs a leak and the volume decreases to 1/2 of the original amount before you can plug the leak, how many moles of gas have you lost (temperature and pressure remain the same)?
Answer:
Explanation:
When volume of gas is V , pressure is P and temperature is T , if n be number of moles of gas
PV / RT = n , R is universal gas constant .
When volume becomes .5 V , pressure P and temperature T
number of moles = Px .5 V / RT = .5 PV / RT = .5 n
Number of moles of gas becomes half .
so 4 moles becomes 2 moles
No of moles lost = 4 - 2 = 2 moles.
Determine the density of CO2 gas at STP
Answer:
the density of CO2 gas at STP is 1.96 g/l.
Convert 85km/hr to cm/s(factor label conversion)
Answer:
23.61m/s
Explanation:
Km/hr is a unit of expressing the speed of a body. Speed is the rate of change of distance with time. Also, the same unit is applicable for expressing the velocity of a body. But to find the velocity, we must emphasize the direction of motion of the body.
Given parameter:
85km/hr to cm/s
Note:
1000m =1km
3600s = 1hr
So;
85 x
Cancelling out km and hr;
= 85 x 0.278m/s
= 23.61m/s
ammonia is______a base
Answer:
Ammonia is moderately a base