Answer:
(a)
From surrounding to wax
(b)
Q = 2.62 KJ
(c)
Density of a substance is defined as the no. of particles of the substance, that occur in a unit volume. So, when the substance melts, the inter-molecular attractive forces and bonds between molecules or atoms are weakened. This, increases the distance between the molecules or atoms. Hence, the no. of particles in a unit volume is decreased. As, a result of this, the density of the substance also decreases.
Explanation:
(a)
During the melting process, the solid material or substance requires energy, in order to break the bonds between its molecules or atoms.
Therefore, while the wax is melting, the net flow of thermal energy is from surrounding to the wax.
(b)
The amount of energy required to melt solid paraffin wax is given by the formula:
Q = nC
where,
Q = amount of energy
C = Molar Heat of Fusion = 48.78 KJ/mol
n = No. of Moles = Mass in gram/Molar Mass = (15.2 g)/(282.62 g/mol)
n = 0.0538 mol
Therefore,
Q = (0.0538 mol)(48.78 KJ/mol)
Q = 2.62 KJ
(c)
Density of a substance is defined as the no. of particles of the substance, that occur in a unit volume. So, when the substance melts, the inter-molecular attractive forces and bonds between molecules or atoms are weakened. This, increases the distance between the molecules or atoms. Hence, the no. of particles in a unit volume is decreased. As, a result of this, the density of the substance also decreases.
(a) During the melting of wax, the flow of thermal energy has been from the surroundings to the wax.
(b) The amount of heat requires for the melting of 15.215 grams of solid paraffin has been 2.62 kJ.
(c) The density decreases due to a decrease in the number of molecules per unit volume.
(a) Melting results in the conversion of solid-state to the liquid state. This step requires energy. Thus, the flow of energy has been from the surroundings to the wax.
(b) Amount of heat requires (Q) can be given by:
Q = nC
Where, n = moles of the sample, and C = heat of fusion
Moles of paraffin = [tex]\rm \dfrac{weight}{molecular\;weight}[/tex]
Moles of paraffin = [tex]\rm \dfrac{15.215}{286.62}[/tex]
Moles of paraffin = 0.0538 moles
Q = 0.0538 [tex]\times[/tex] 48.78 kJ/mol
Q = 2.62 kJ.
The amount of heat requires for the melting of 15.215 grams of solid paraffin has been 2.62 kJ.
(c) The density has been the mass or number of particles present per unit volume. The melting of wax results in a weaker intermolecular force. The resulting liquid will have fewer molecules present in the unit volume.
Thus, the density decreases due to a decrease in the number of molecules per unit volume.
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What is the amount of energy needed to heat 2.3 g of aluminum from 6.2oC to 46.9oC in Joules?
Answer:
Heat required = 84.25 Joule
Explanation:
Heat required = mass × specific heat capacity × temperature change
Specific heat capacity of aluminium = 0.90 J/g/K
Heat required = 2.3 × 0.9 × (46.9 -6.2)
= 84.25 Joules
If you want to produce 11 moles of NH3, how much H2 do you need?
Answer:
33 g of H2
Explanation:
N2 + 3 H2 -> 2 NH3
3 mol H2 -> 2 mol NH3
x -> 11 mol NH3
x= (11 mol NH3 * 3 mol H2)/ 2 mol NH3
x= 16.5 mol H2
1 mol H2 -> 2 g
16.5 mol H2 ->x
x= (16.5 mol H2 * 2 g)/ 1 mol H2
x= 33 g
Nitric acid can be formed in two steps from the atmospheric gases nitrogen and oxygen, plus hydrogen prepared by reforming natural gas. In the first step, nitrogen and hydrogen react to form ammonia:
N2 (g)+ 3H2(g) → 2NH3(g)
In the second step, ammonia and oxygen react to form nitric acid and water:
NH3(g)+ 2O2(g) → HNO3(g) + H2O(g)
Calculate the net change in enthalpy for the formation of one mole of nitric acid from nitrogen, hydrogen and oxygen from these reactions. Round your answer to the nearest .
Answer:
-376 kJ.
Explanation:
give the systematic name for the following compound
Answer:
2,4–dimethylhexane.
Explanation:
To name the above compound, we must do the following:
1. Locate the longest continuous carbon chain. This gives the parent name. In this case, the longest chain is carbon 6 i.e Hexane.
2. Identify and Locate the position of the substituent group attached. In this case, the substituent group attached is methyl i.e CH3 and it is at carbon 2 and 4.
3. Combine the above to get the name.
Therefore, the name of the compound is:
2,4–dimethylhexane.
state the purpose of respiration.
Answer:
The purpose of respiration is to supply the body with oxygen and eliminate carbon dioxide. Oxygen is essential for cellular respiration as cells cannot exist in the absence of it. The human lungs are the organs responsible for respiration.
Explanation:
Respiration refers to a person’s breathing and the movement of air into and out of the lungs. The respiratory system provides oxygen to body tissues for cellular respiration, removes the waste product carbon dioxide, and helps maintain acid–base balance. Inspiration is the process that causes air to enter the lungs, and expiration is the process that causes air to leave the lungs . A respiratory cycle (or one breath while you are measuring respiratory rate) is one sequence of inspiration and expiration.
Predict the products of the following reactions (assume complete reaction). In your submission include the overall balanced equation, and balanced net ionic equation if applicable:
a. Adding zinc metal to a solution of copper(II) sulfate
b. Dripping silver perchlorate into a solution of sodium carbonate
c. A lump of aluminum metal is dropped into concentrated hydroiodic acid
d. Sucrose is fermented in water by yeast to make ethanol and carbon dioxide (note: water is a reactant)
e. Solid calcium oxide is added to water (careful)
f. A lump of potassium metal is dropped into water (careful)
Answer:
Zn(s) + CuSO4(aq) -----> ZnSO4(aq) + Cu(s)
Na2CO3 (aq)+ 2AgClO4(aq) → 2NaClO4(aq) + Ag2CO3(s)
2Al(s) + 6HI(aq) ------> 2AlI3(aq) + 3H2(g)
C12H22O11(s)+H2O(l)→4C2H5OH(aq)+4CO2(g)
2K(s) + 2H2O(l) ------->2KOH(aq) + H2(g)
Explanation:
In the first reaction, zinc displaces copper from an aqueous copper II salt since zinc is higher than copper in the electrochemical series.
Reaction two leads to the precipitation of silver carbonate. Remember that carbonates are mostly insoluble in water.
Acids are known to displace hydrogen gas from dilute acids. Hence in the third reaction, aluminum displaced hydrogen from aqueous hydroiodic acid.
In the fourth reaction, the action of yeast leads to the fermentation of sucrose yielding ethanol and carbon dioxide in the process.
Metals are known to form aqueous alkaline solutions liberating hydrogen gas when they react with water. Hence potassium metal reacts with water to liberate hydrogen gas and form alkaline potassium hydroxide.
what was the open-range system
Answer: In the Western United States and Canada, open range is rangeland where cattle roam freely regardless of land ownership. ... Land in open range that is designated as part of a "herd district" reverses liabilities, requiring an animal's owner to fence it in or otherwise keep it on the person's own property.
Explanation: Mark me as brainliest
1. What is the answer to the following expression in the correct number of significant figures?
(0.1245) x (0.00003) x (298,000)/(2.0 - 1.5)
Answer:
2 with 1 SF
Explanation:
If it's a summer day and you want to take a picnic are you concerned with weather
or climate? Why?
Answer:
Not really, the chances you will get hurt are insignificant
Explanation:
weather balloon is filled with helium to a volume of 340 L at 30 ∘C and 751 mmHg . The balloon ascends to an altitude where the pressure is 495 mmHg and the temperature is -27 ∘C.What is the volume of the balloon at this altitude?
Answer: Thus the volume of the balloon at this altitude is 419 L
Explanation:
Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.
The combined gas equation is,
[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]
where,
[tex]P_1[/tex] = initial pressure of gas = 751 mm Hg
[tex]P_2[/tex] = final pressure of gas = 495 mm Hg
[tex]V_1[/tex] = initial volume of gas = 340 L
[tex]V_2[/tex] = final volume of gas = ?
[tex]T_1[/tex] = initial temperature of gas = [tex]30^oC=273+30=303K[/tex]
[tex]T_2[/tex] = final temperature of gas = [tex]-27^oC=273-27=246K[/tex]
Now put all the given values in the above equation, we get:
[tex]\frac{751\times 340}{303}=\frac{495\times V_2}{246}[/tex]
[tex]V_2=419L[/tex]
Thus the volume of the balloon at this altitude is 419 L
After spraying water on a waxed surface, a student notices that the water beads up to form many individual drops rather than being spread out evenly across the surface. What property of water causes it to bead up like this?
A.The high boiling point of water
B.The strong adhesion to other substances
C. The high density of liquid water
D.The ability to dissolve many other substances
E. The strong cohesion between water molecules
Answer:
B. The strong adhesion to other substances
Explanation:
hope this helps!
Answer:
E. The strong cohesion between water molecules
Explanation:
Water is a very special molecule because of its hydrogen bonds. And, because of these hydrogen bonds, water has many properties that make it unique compared to other substances.
One such property is that it is cohesive, which means water molecules are attracted to each other. This is due to the polar bonds and hydrogen bonds that water molecules have. Because of the polar and hydrogen bonds, the molecules attract each other and stick together, creating that bead-like phenomenon that the student sees on the table.
Thus, the answer is E.
How many atoms are in 4Ca3(PO4)2
Answer:
52
I personally don't know how to do this but this is what I was told the answer is
There are 22 atoms in calcium phosphate with chemical formula 4 Ca₃(PO₄)₂ .
To determine the number of atoms in a chemical formula, one need to multiply the number of atoms for each element by the corresponding subscript and then sum them up.
In the given chemical formula, 4 Ca₃(PO₄)₂, :
- 4 is the coefficient in front, indicating that the entire compound is multiplied by 4.
- Ca represents calcium, and the subscript 3 indicates there are 3 calcium atoms.
- (PO₄)₂ represents a group called a phosphate group. Within the phosphate group, we have 1 phosphorus atom (P) and 4 oxygen atoms (O). The subscript 2 outside the parentheses indicates that the entire phosphate group is multiplied by 2.
To calculate the total number of atoms, we multiply the coefficients by the subscripts and sum them up:for calcium (Ca):
3 calcium atoms × 4 = 12 calcium atoms
For phosphate:
1 phosphorus atom ×2 = 2 phosphorus atoms
4 oxygen atoms ×2 = 8 oxygen atoms
Adding up the totals:
12 calcium atoms + 2 phosphorus atoms + 8 oxygen atoms = 22 atoms
Therefore, there are 22 atoms in 4 Ca₃(PO₄)₂.
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How many moles would needed to be dissolved in 1 dm3 to get a 3M solution? How many would be needed if only 0.1 dm3 were used?
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Answer:
I dm u on Instagram
Explanation:
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According to molar concentration, 3 moles are needed to be dissolved in 1 dm³ to get a 3 M solution,and 0.3 moles would be needed if only 0.1 dm³were used.
What is molar concentration?Molar concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molar concentration is moles/liter.
The molar concentration depends on change in volume of the solution which is mainly due to thermal expansion. Molar concentration is calculated by the formula, molar concentration=mass/ molar mass ×1/volume of solution in liters.
In terms of moles, it's formula is given as molar concentration= number of moles /volume of solution in liters.Substituting the values in given formula, number of moles=molar concentration×volume in liters=3×1=3 moles and for 0.1 dm³ it is 3×0.1=0.3 dm³.
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The decomposition of nitrogen dioxide is described by the following chemical equation:
2NO_2 (g) --------> 2NO (g) + O_2 (g)
Suppose a two-step mechanism is proposed for this reaction, beginning with this elementary reaction:
NO_2 (g) --------> NO_(g) + O_(g)
Suppose also that the second step of the mechanism should be bimolecular.
a) Suggest a reasonable second step. That is, write the balanced chemical equation of a bimolecular elementary reaction that would complete the proposed mechanism.
Answer:
The balanced chemical equation will be "[tex]NO_{2}+O\rightarrow NO+O_{2}[/tex]".
Explanation:
The given equation is:
[tex]2NO_{2}\rightarrow 2NO+O_{2}[/tex]
Step 1:
[tex]2NO_{2}\rightarrow NO+O[/tex]...(equation 1)
Step 2:
[tex]NO_{2}+O\rightarrow NO+O_{2}[/tex]...(equation 2)
On adding "equation 1" and "equation 2", we get
⇒ [tex]NO_{2}+NO_{2}+O\rightarrow NO+O+NO+O_{2}[/tex]
⇒ [tex]2NO_{2}\rightarrow 2NO+O_{2}[/tex]
The second step:
⇒ [tex]NO_{2}+O\rightarrow NO+O_{2}[/tex]
If 100 ml of a 0.75 m hno3 is required to exactly neutralize 50 ml of naoh what is the concentration of the base?
Answer:
1.5M
Explanation:
M1V1=M2V2
(0.75M)(100ml)=(M2)(50 ml)
M2= 1.5 M
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the _ is responsible for absorbing the most uv radiation
Use one of your experimentally determined values of k, the activation energy you determined, and the Arrhenius equation to calculate the value of the rate constant at 25 °C. Alternatively, you can simply extrapolate the straight-line plot of ln(k) vs. 1/T in your notebook to 1/298, read off the value of ln(k), and determine the value of k. Please put your answer in scientific notation. slope=-12070, Ea=100kJ/mol, k= 0.000717 (45 °C), 0.00284 (55 °C), 0.00492 (65 °C), 0.0165 (75 °C), 0.0396 (85 °C).
Answer:
Explanation:
Use one of your experimentally determined values of k, the activation energy you determined, and the Arrhenius equation to calculate the value of the rate constant at 25 °C. Alternatively, you can simply extrapolate the straight line plot of ln(k) vs. 1/T in your notebook to 1/298 , read off the value of ln(k), and determine the value of k. Please put your answer in scientific notation. slope=-12070, Ea=100kJ/mol, k= 0.000717(45C), 0.00284(55C), 0.00492(65C), 0.0165(75C), 0.0396(85C)
Explanation;
According to Arrhenius equation:
i.e. ln(k2/k1) = -Ea/R (1/T2 - 1/T1)
Where, k1 = 0.000717, T1 = 45 oC = (45+273) K = 318 K
T2 = 25 oC = (25 + 273) K = 298 K
i.e. ln(k2/0.000717) = -12070 (1/298 - 1/318)
i.e. ln(k2/0.000717) = -2.54738
i.e. k2/0.000717 = [tex]e^{-2.54738}[/tex]
= 0.078286
Therefore, the required constant (k2) = 0.078286 * 0.000717 = [tex]5.61*10^-^5[/tex]
What is the relationship between heat, temperature, thermal
energy within a system?
Answer:
The thermal energy, orheat, of an object is obtained by adding up the kinetic energy of all the molecules within it.Temperature is the average kineticenergy of the molecules.
how does an organic pH indicator works. (illustrate using chemical equations and
mathematical expressions
Answer:
A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually. Hence, a pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+) in the Arrhenius model.A pH of 7 indicates a neutral solution like water. A pH less than 7 indicates an acidic solution and a pH greater than 7 indicates a basic solution. Ultimately, the pH value indicates how much H+ has dissociated from molecules within a solution. The lower the pH value, the higher concentration of H+ ions in the solution and the stronger the acid. Likewise, the higher the pH value, the lower the concentration of H+ ions in the solution and the weaker the acid.
Explanation:
what is 2H2O state of matter
Answer:
2 MOLECULES OF WATER
Explanation:
SO, LIQUID
which of the following can cause acid precipitation
the use of solar panels
the use of hydroelectricity
the use of coal
all of the above
Answer:
C. The use of coal
Explanation:
Answer:
C. The use of coal
Explanation:
Edge 2021
What is a paragraph to fit this
Answer:
They add carbon Dioxide into the air warming the atmosphere which adds to the greenhouse effect, Making the temperature higher
WHOSE Good with Chemistry to figure this question out?
Calculate the work in joules if the external pressure is 825 torr.
Remeber 1 L atm = 101.3 J
Answer:
[tex]\large \boxed{\text{220 J}}[/tex]
Explanation:
1. Convert the pressure to atmospheres
[tex]p = \text{825 Torr} \times \dfrac{\text{1 atm}}{\text{760 Torr}} = \text{1.086 atm}[/tex]
2. Calculate the work done
[tex]w = -p\Delta V = -p(V_{f} - V_{i}) = -\text{(1.086 atm)}(\text{2.0 L - 4.0 L})\\\\ = -\text{1.086 atm} \times \text{(-2.0 L)} = \text{2.17 L$\cdot$atm}[/tex]
3. Convert litre atmospheres to joules
[tex]w = \text{2.17 L$\cdot$atm} \times \dfrac{\text{101.3 J}}{\text{1 L$\cdot$atm}} = \textbf{220 J}\\\\\text{The work done is $\large \boxed{\textbf{220 J}}$}[/tex]
Note that the volume is decreasing, so work is being done on the system.
Use your Cabbage pH Indicator Key to determine the pH of each. Enter the pH ranges into the data table.
Answer: pH :1-2 / acid
pH:7/neutral
pH:8-9/basic
Your welcome
Answer:1-2,7, 8-9
Explanation:
Acidic, neutral, basic
The chart below describes the molecular motion in solids, liquids, gases, and plasma.
Solids Liquids Gases Plasma
slower than liquids, slower than solids but faster than solids faster than solids,
gases, and plasma faster than gases and but slower than liquids and gases
plasma plasma
The information in the chart about molecular motion is incorrect for:______
1. solids
2. liquids
3. gases
4. plasma
Answer:
Liquids
Note: the attachment below shows the properly arranged chart
Explanation:
The order of molecular motion of matter from fastest to slowest is;
Plasma>Gases>Liquids>Solids
Liquids move faster than solids not slower.
Answer:
liguids
Explanation:
Why are white Americans less affected by toxic waste and air pollution than people of color?
A.They tend to live in urban centers .
B. They tend to vote in smaller numbers compared to other groups.
C. They tend to have more of a say in where uncontrolled toxic waste sites are located.
D. All of the above are true.
Answer:
D. All the above
Explanation:
WHite people are "previlged"
How many miles of glucose are in 19.1 g of glucose
Answer:
did you mean moles? If so, answer is down below.
Explanation:
there are 0.106 moles of glucose in 19.1 g of glucose.
what is a respiration?
Answer:
Respiration is the biochemical process in which the cells of an organism obtain energy by combining oxygen and glucose, resulting in the release of carbon dioxide, water, and ATP (the currency of energy in cells)
Explanation:
Which multimedia does this ad from the Centers for Disease Control’s advertising campaign for the flu vaccine include? (more than one)
A.) animation
B.) image
C.) text
D.) graph
E.) chart
Answer:
Image and text
Explanation:
on edge
5. Which of the following is NOT a physical change?
nailing together boards of wood
breaking an egg
dying your hair
adding food coloring to water