Answer:
Everything around you can be broken down into smaller particles called atoms. The particles of one substance are all the same and different substances are made up of different particles.
Explanation:
The Rf value of compound A is 0.34 when a TLC plate is developed in pentane and 0.44 when the plate is developed in diethyl ether. Compound B has an Rf value of 0.42 in pentane and 0.60 in diethyl ether. Which solvent would be better for separating a mixture of A and B by TLC?
Answer:
Diethyl ether
Explanation:
The retention factor is measure of how much interaction that exists between the solvent and the solutes. A high retention factor means that the solute travels too quickly through the mobile phase.
The value of Rf shows how good a solvent is in achieving separation of the components of a mixture by TLC.
If the Rf is moderate, then the solute does not travel too quickly through the column. If the solute travels too quickly through the column(too high Rf), minimum separation is achieved. If the Rf is too low, the solute has more affinity for the stationary phase than it does for the mobile phase hence separation is not feasible.
We can see that in both cases, diethyl ether has a moderate Rf hence it achieves a better separation of compound A and B than pentane.
A physical change :_______
a) occurs when water is evaporated.
b) occurs when glucose is converted into energy within your cells.
c) occurs when sugar is heated into caramel
d) occurs when iron rusts.
1. Rank the following solutions from least polar to most polar. Rank on a scale of 1-4: 1 being the least polar and 4 being the most polar. _______ 50% ISOPROPANOL / H2O _______ 25% ISOPROPANOL / H2O _______ PURE WATER _______ ISOPROPANOL / H2O
Answer:
50% ISOPROPANOL / H2O - 1
25% ISOPROPANOL / H2O - 2
Pure water - 4
ISOPROPANOL / H2O - 3
Explanation:
More Isopropanol concentration is least polar. When the isopropanol is mixed with water its polarity increases. Pure water is most polar. The polarity of a substance is dependent on its ability to bent and mold in the shape as required.
Density of a substance can be used as unit factor for conversion between mass and volume: then the If 20 g of gold (density 19.3 g/cm), the corresponding volume that gold will occupy is
Answer:
density = d = 19.3g/cm^3
Mass of gold = m= 20g
now
we know,
density = mass / volume
or volume = mass/ density
volume = 20/19.3 = 1.036cm^3
Explanation:
Draw a Lewis structure for SF4 that has minimized formal charges. Include all nonbonding electrons and any nonzero formal charges.
Answer:
See explanation and image attached
Explanation:
The compound SF4 is sulphur tetraflouride. It has a zero formal charge and has a total of 34 valence electrons.
The central atom in the molecule is sulphur in an sp3d hybridization state hence the molecule has a trigonal bipyramidal electron geometry. Since it is a molecule of the sort AX4E; it gives a see-saw molecular shape.
The structure of the molecule is shown in the image attached to this answer.
In the Lewis structure of SF₄ , sulfur (S) is the central atom bonded to four fluorine (F) atoms. Lewis structure for SF₄ is attached to the image below.
Each bond is represented by a line, indicating a pair of shared electrons between the bonded atoms. The fluorine atoms are placed around the sulfur atom, and each fluorine atom has a lone pair of electrons that are not involved in bonding.
Sulfur (S) is in Group 16 of the periodic table, so it has 6 valence electrons. Fluorine (F) is in Group 17 and has 7 valence electrons each.
Since we have 4 fluorine atoms, add 4 times the number of valence electrons for fluorine (4 × 7 = 28). The total number of valence electrons in SF₄ is 6 + 28 = 34.
Since each fluorine atom requires 8 electrons (octet rule), each F atom will have 6 lone pairs (12 electrons) around it.
The sulfur atom (S) has a formal charge of +2 (6 valence electrons - 4 bonds - 0 lone pairs), while the fluorine atoms (F) have a formal charge of -1 (7 valence electrons - 0 bonds - 6 lone pairs).
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What is another name for North East trade winds?
Answer:
Because winds are named for the direction from which the wind is blowing, .Explanation: the winds are called the northeasterly trade winds in the Northern Hemisphere and the southeasterly trade winds in the Southern Hemisphere.
Some objects can store more thermal energy than others.
A. True
b. False
Answer:
A. True
Explanation:
is the law of conservative mass observed in this equation CaCO3 + 2HCI -->CaCI2 +H2O + CO2
Answer:
The law is observed in the given equation.
Explanation:
CaCO₃ + 2HCI → CaCI₂ +H₂O + CO₂
In order to find out if the law of conservative mass is followed, we need to count how many atoms of each element are there in both sides of the equation:
Ca ⇒ 1 on the left, 1 on the right.C ⇒ 1 on the left, 1 on the right.O ⇒ 3 on the left, 3 on the right.H ⇒ 2 on the left, 2 on the right.Cl ⇒ 2 on the left, 2 on the right.As the numbers for all elements involved are the same, the law is observed in the given equation.
a sample of cobalt, A, with a mass of 5.00g, is initially at 25 C. When this sample gains 6.70 J of heat, the temperature rises to 27.9 C. Another sample of cobalt, B, with a mass of 7.00 g, iw initially at 25 C. If sample B gains 5.00 J of heat, what is the final temperature of sample B
Answer:
26.5°C
Explanation:
We can solve this question using the equation:
q = m*S*ΔT
Where Q is heat gained in joules, m is the mass of the sample, S is specific heat and ΔT change in temperature.
With the sample A we can find specific heat of cobalt in order to find, in sample B, the ΔT and the final temperature:
Sample A:
q = m*S*ΔT
6.70J = 5.00g*S*(27.9°C-25.0°C)
0.462J/g°C = Specific heat of cobalt
Sample B:
q = m*S*ΔT
5.00J = 7.00g*0.462J/g°C*ΔT
1.5°C = ΔT
As the initial temperature of sample B is 25°C, final temperature is:
25°C + 1.5°C = 26.5°C
What is the specific heat of a metal if it takes 26.5 calories to raise the temperature of a piece weighing 50.0 g by 5.00 Celsius degrees
Answer:
The specific heat of the metal is 0.106 [tex]\frac{cal}{g*C}[/tex]
Explanation:
Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
There is a direct proportional relationship between heat and temperature. The constant of proportionality depends on the substance that constitutes the body as on its mass, and is the product of the specific heat by the mass of the body. So, the equation that allows calculating heat exchanges is:
Q = c * m * ΔT
where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.
In this case:
Q= 26.5 cal (calories)c= ?m= 50 gΔT= 5 CReplacing:
26.5 cal= c* 50 g* 5 C
Solving:
[tex]c=\frac{26.5 cal}{50g*5 C}[/tex]
c= 0.106 [tex]\frac{cal}{g*C}[/tex]
The specific heat of the metal is 0.106 [tex]\frac{cal}{g*C}[/tex]
1. You find a separatory funnel set up in a fume hood. There are clearly two visible layers. Describe a method you could use to determine which layer is the aqueous layer.
Answer:
You find a separatory funnel set up in a fume hood. There are clearly two visible layers. Describe a method you could use to determine which layer is the aqueous layer.
Explanation:
In the separating funnel, the liquid with less density exists at the top layer and the liquid with greater density will exist at the bottom layer.
To identify the aqueous layer, add a bit of water to the separating funnel.
Then, observe where the water will go and mix.
If it mixes with the bottom layer, then the bottom layer is the aqueous layer.
If water mixes with the top layer, then top layer is the aqueous layer.
A method we could use to determine which layer is the aqueous layer is by adding 2-4 drops of water in the separatory funnel.
Explanation:
A separatory funnel is a glass apparatus used in labs to separate two immiscible liquids from each other.The two liquids will be present distinctly in form of two different layers one on the other.The liquid at the bottom is with higher density in comparison to the liquid layer at the top which is with lower density.It is mainly used to separate the layer of organic compounds from the aqueous layer.One way to determine the aqueous layer in the separatory funnel is to add 2-4 drops of water to the separatory funnel and observe in which layer the water drops get invisible that is mixed up.The layer in which water drop mixes will experience a small increase in its volume and that will be the aqueous layer.Water drops will not mix with the organic layer can be easily observed with eyes.So, from this, we can conclude that a method we could use to determine which layer is the aqueous layer is by adding 2-4 drops of water in the separatory funnel.
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Given the following liquids and their boiling points, which has the highest vapor pressure at its normal boiling point?
a) ethanol, bp = 78°C
b) methanol, bp = 65°C
c) water, bp = 100°C
c) benzene, bp = 80°C
d) The vapor pressure of each of the liquids at its normal boiling point would be the same.
Answer:
b) methanol, bp = 65°C.
Explanation:
Hello there!
In this case, it turns out necessary for us to firstly remember that the vapor pressure of a liquid is the pressure exerted by the gaseous particles in dynamic equilibrium with the present liquid and thus, the higher the vapor pressure, the weaker the liquid's intermolecular forces because they turn unstable.
In such a way, we can infer that the liquid with the highest vapor pressure, will have the lowest boiling point and therefore, the answer will be b) methanol, bp = 65°C.
Regards!
12. Which formula shows a substance that is not molecular?
H₂
H2O
н
CO2
Answer:
the answer is H ..............
1) 7.269 moles of oxygen gas are used in combusting butane (C H..). How many moles of carbon dioxide
gas are produced? You must start with a balanced chemical equation. Start with a balanced equation
Explanation:
C4H10 + 13/2O2 ---------> 4CO2 + 5H2O
so u can work out the amount of moles by doing
moles=mass/mr
mr of C4H10 is 12 × 4 + 10 =58
=7.269/58
= 0.125moles
Then u can use the molar ratio which is
6.5:4
0.125 ÷6.5 × 4 = 0.0769moles
hope this helps:)
If you had used toluene instead of methyl benzoate in this reaction, what nitration product(s) would have formed? Write a stepwise mechanism for the nitration reaction of toluene.
Answer:
See explanation
Explanation:
The electrophilic substitution of aromatic compounds occurs faster in substituted aromatic compounds due to the fact that the ring becomes more or less susceptible to electrophilic attack depending on the nature of the substituent in the ring.
Electron pushing substituents such as alkyl groups stabilize the positive charge developed during electrophilic substitution hence they activate the ring towards electrophilic substitution.
The methyl group is an ortho - para directing substituent hence the product obtained by nitration of toluene is o-nitrotoluene and p-nitrotoluene.
The stepwise mechanism for obtaining these products is shown in the image attached to this answer.
Avagadro’s number:
A: Is constant irrespective of mass of the gases
B: Varies according to the mass of the gases
C: Varies according to the pressure on the gases
D: All of the Above
Answer:
A: Is constant irrespective of mass of the gases
Explanation:
Avagadro's number, denoted by nA, is a number that represents the units in one mole of any substance. The number is 6.02214076 × 10²³ and the units can be atoms, molecules, ions, formula units etc.
That is;
1 mole of a substance = 6.022 × 10²³atoms, molecules, ions, electrons etc.
It is important to note that the Avagyadro's number is constant irrespective of mass of the gases that are involved.
Please help me ASAP
Which of the following pairs of atoms is most likely to form an ionic bond?
lithium and sodium
sodium and neon
sulfur and oxygen
lithium and sulfur
Answer:
lithium and sulfur
Explanation:
An ionic bond is formed between a metal, which loses electrons to form a cation, and a non-metal, which gains electrons to form an anion.
Which of the following pairs of atoms is most likely to form an ionic bond?
lithium and sodium. NO. Both are metals. sodium and neon. NO. Sodium is metal and neon is a noble gas. sulfur and oxygen. NO. Both are non-metals. lithium and sulfur. YES. Lithium is metal and sulfur non-metal.Is benzene a solute or solvent
Ketone bodies are produced when a person what
Answer:
Ketones and ketoacids are alternative fuels for the body that are made when glucose is in short supply. They are made in the liver from the breakdown of fats. Ketones are formed when there is not enough sugar or glucose to supply the body's fuel needs. This occurs overnight, and during dieting or fasting.
Explanation:
5.96 g of ammonia reacts completely according to the following reaction:
2 NH3, (g) + Co2, (g) → CN2,OH4, (s) + H20 (l)
(a) What is the theoretical yield of urea (CN,OH,) for this reaction?
(b) If 13.74 g of urea are produced, what is the percent yield for this equation?
please show work, will give brainliest
Explanation:
hope this helps you to understand :)
The theoretical yield of urea (CN, O, H,) for this reaction is = 9.88 g of urea
The percent yield for this equation is 176%
What is a chemical reaction?
A chemical reaction is a procedure in which one or more materials are transformed into one or extra unique materials. inside the response, the atoms of the beginning materials are rearranged, forming new substances which have specific residences.
calculation:-
2 NH3, (g) + Co2, (g) → CN2,OH4, (s) + H20 (l)
2*17 g of ammonia produces 60g of urea.
5.6 g of ammonia produces = (60/34)*5.6
= 9.88 g of urea
60g of urea produced by 34 g of ammonia
13.74 g of urea produced by =34/60*13.74
= 7.78 g
percentage yield = 13.74 g of urea are produced/7.78
=1.76*100
⇒ 176%
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50.0 g of Potassium chloride reacts with 50.0 g of oxygen to produce KCIO3. After writing
and balancing the reaction, determine the amount of potassium chlorate produced
128 g
32.0 g
082.2 g
None of these answers.
Explanation:
If 50.0 grams of Zinc are reacted with 50.0 grams of Hydrogen Chloride ... 50.09 Zn x 1 mol Zn , Imol ZnCl2 , 136.4g. ... If a decomposition reaction produces a 75.0% yield for the oxygen by mass (128.0 grams were.
If the pH is 9 what is the concentration of hydroxide ion [OH]? (hint: find the pOH first)
How would you classify cloudy water as an abiotic factor? Human Impact, Dynamic Forces, or Ocean Chemistry.
Answer:
Option B, Dynamic force
Explanation:
Cloudy water is an abiotic factor as it cannot support life and it is produced due to the impact of Dynamic Forces.
Cloudy water consists of air bubbles and is harmless.
Biotic things have life and posses characteristics of living beings such as eating, walking, reproducing etc.
Aqueous potassium carbonate was mixed with aqueous copper (1) fluoride and a crystallized copper (1) carbonate product was formed. A crystalized product is a solid. The other product, potassium fluoride, remains dissolved in solution. Consider the other product and it’s phase, and then write the balanced molecular equation for this precipitation reaction. Express your answer as a chemical equation including phases. Type an underscore (_) or a carat (^) to add subscripts and superscripted more quickly.
Answer: The balanced molecular equation for the precipitation reaction is [tex]K_2CO_3(aq)+2CuF(aq)\rightarrow Cu_2CO_3(s)+2KF(aq)[/tex]
Explanation:
A precipitation reaction is defined as the reaction where a solid precipitate (solid substance) is formed at the end of the reaction. It is insoluble in water.
When potassium carbonate reacts with copper (I) fluoride, it leads to the formation of solid copper (I) carbonate and potassium fluoride solution.
The balanced chemical equation follows:
[tex]K_2CO_3(aq)+2CuF(aq)\rightarrow Cu_2CO_3(s)+2KF(aq)[/tex]
The precipitate formed is copper (I) carbonate
which of the following is true about the action-reaction forces encountered in Newton’s third law
A. always cancel each other out
B always act on different objects
C are always the same as normal and frictional forces
D None of the above
Explanation:
D)None of the above!!!!
B: Always act on different objects
4. Complete the following equations:
CuCl2 + Na2CO3 → 2 NaCl +............
FeSO4 + BaCl2 →
Cu(NO3)2 + CaCO3
Answer:
2NaCl + CuCO3
FeCl2 + BaSO4
CuCO3 + Ca(NO3)2
Explanation:
Presumably this is a double replacement reaction.
A+B + C+D → A+D + C+B
It seems I may be wrong so please try to work out the problem yourself to double check, keeping in mind the charges of each compound.
What is the reduction half-reaction for the equation below?
5Fe2+(aq) + MnO4" (aq) + 8H+(aq) → 5Fe3+ (aq) + Mn2+(aq) +
4H2O(1)
Answer:
[tex]MnO_4^-+8H^++5e^-\rightarrow Mn^{2+}+4H_2O[/tex]
Explanation:
Hello there!
In this case, since redox reactions are characterized by the presence of a reduction reaction, whereby the oxidation of the element decreases, and an oxidation reaction whereby the oxidation of the element increases.
In such a way, for the given chemical equation, we can see Fe is increasing its oxidation state from 2+ to 3+, which means it is oxidized. On the flip side, Mn is being reduced from 7+ (MnO₄⁻) to 2+ and this, the reduction half-reaction is:
[tex]MnO_4^-+8H^++5e^-\rightarrow Mn^{2+}+4H_2O[/tex]
Whereas five electrons are carried.
Regards!
Which of the following is not a polymer
A. Glucose.
B. Starch.
C. Cellulose.
D. DNA.
Answer:
A. Glucose
Explanation:
Glucose is a monomer and not a polymer. So, option (A) is not a polymer.
Glucose is not a polymer because it is a kind of molecule while Starch , cellulose and DNA are polymers.
The correct answer is option A. Glucose.
why is an alkaline substance dropped into lakes in some countries
Answer:
Lake Treatment
Explanation:
Sulphuric dioxide produced by industries and released into the atmosphere returns as acid rain or sulphuric acid. In lakes impacted by acid rain, such as in Ontario, Canada, the application of alkalis dropped by airplanes can control and neutralize the water's pH level.
140 g of KCl is dissolved in 600 mL of water. What is the molarity?
Answer:
[tex]\boxed {\boxed {\sf molarity \approx 3 \ M \ KCl}}[/tex]
Explanation:
Molarity is a measure of concentration in moles per liter. The formula is:
[tex]molarity= \frac{moles \ of \ solute}{liters \ of \ solution}[/tex]
We are given grams of solute and liters of solution, so we must convert both before calculating molarity.
1. Convert Grams to MolesWe convert grams to moles using the molar mass. This value is found on the Periodic Table. It is the same as the atomic mass, but the units are grams per mole (g/mol) instead of atomic mass units (amu).
We have the compound KCl, so we look up the molar masses of the individual elements.
Potassium (K): 39.098 g/mol Chlorine (Cl): 35.45 g/molThe compound does not contain subscripts, so we can add the molar masses together to find the molar mass of the compound.
Potassium chloride (KCl): 39.098+ 35.45= 74.548 g/molUse the molar mass as a ratio.
[tex]\frac {74.548 \ g\ KCl}{1 \ mol \ KCl}[/tex]
Multiply by 140 grams of KCl.
[tex]140 \ g\ KCl*\frac {74.548 \ g\ KCl}{1 \ mol \ KCl}[/tex]
Flip the ratio so the units of grams of KCl cancel.
[tex]140 \ g\ KCl*\frac{1 \ mol \ KCl} {74.548 \ g\ KCl}[/tex]
[tex]140 *\frac{1 \ mol \ KCl} {74.548 }[/tex]
[tex]1.877984654 \ mol \ KCl[/tex]
2. Convert Milliliters to Liters1 liter contains 1000 milliliters. Create another ratio.
[tex]\frac{ 1 \ L}{1000 \ mL}[/tex]
Multiply by 600 milliliters (the value we are converting).
[tex]600 \ mL *\frac{ 1 \ L}{1000 \ mL}[/tex]
The units of milliliters cancel.
[tex]600 \ *\frac{ 1 \ L}{1000 }[/tex]
[tex]0.6 \ L[/tex]
3. Calculate MolarityNow we know the moles of solute and the liters of solution.
1.877984654 mol KCl and 0.6 LSubstitute the values into the molarity formula.
[tex]molarity= \frac {1.877984654 \ mol \ KCl}{0.6 \ L}[/tex]
[tex]molarity= 3.129974424 \ mol \ KCl/L[/tex]
The original measurements of grams and milliliters have 2 and 1 significant figures. We must round our answer to the least number of sig figs: 1.
For the number we found, that is the ones place. The 1 in the tenths place tells us to leave the 3 in the ones place.
[tex]molarity \approx 3 \ mol \ KCl/L[/tex]
1 mole per liter is equal to 1 molar or M. Convert the units.
[tex]molarity \approx 3 \ M \ KCl[/tex]
The molarity is approximately 3 M KCl.