Answer:
false
Explanation:
energy does not return to the sun, it returns to the plants or producers. if energy were to return to the sun, it would have to travel though space.
It is important for scientists to know how much energy is given off or absorbed in a chemical reaction. Which options below would indicate an exothermic reaction?
delta H = –
delta H = +
Energy is considered a reactant in the reaction: A + B + energy ---> C + D
Energy is considered a product in the reaction: A + B ---> C + D + energy
Energy is released in the reaction.
Energy is absorbed in the reaction.
For exothermic reactions, ΔH is always negative, energy is considered a product, and energy is released in the reaction.
An exothermic reaction is one in which energy, usually in the form of heat, is released to the environment from the reaction. In other words, the final temperature of an exothermic reaction would always be more than the initial temperature.
This also means that heat energy is a product of exothermic reactions and this heat is released to the environment from the reaction.
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Answer:
a, d, and e is correct on edge of the nuity
Explanation:
have a good day
Many computer chips are manufactured from silicon, which occurs in nature as SiO2. When SiO2 is heated to melting, it reacts with solid carbon to form liquid silicon and carbon monoxide gas. In an industrial preparation of silicon, 155.0 kg of SiO2 is allowed to react with 78.2 kg of carbon to produce 66.0 kg of silicon.
Required:
a. What is the theoretical yield for the reaction in Kg Si?
b. What is the percent yield for the reaction?
Answer:
(a): The theoretical yield of silicon is 72.33 kg.
(b): The percent yield of the reaction is 91.25 %.
Explanation:
Limiting reagent is defined as the reagent which is completely consumed in the reaction and limits the formation of the product.
Excess reagent is defined as the reagent which is left behind after the completion of the reaction.
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] .....(1)
For [tex]SiO_2[/tex]:
Given mass = 155.0 kg = 155000 g (Conversion factor: 1 kg = 1000 g)
Molar mass = 60 g/mol
Putting values in equation 1:
[tex]\text{Moles of }SiO_2=\frac{155000g}{60g/mol}=2583.3mol[/tex]
For carbon:
Given mass = 78.2 kg = 78200 g
Molar mass = 12 g/mol
Putting values in equation 1:
[tex]\text{Moles of carbon}=\frac{78200g}{12g/mol}=6516.67mol[/tex]
The chemical equation for the reaction of silicon dioxide and carbon follows:
[tex]SiO_2+2C\rightarrow Si+2CO[/tex]
By stoichiometry of the reaction:
1 mole of [tex]SiO_2[/tex] reacts with 2 moles of carbon
So, 2583.3 moles of [tex]SiO_2[/tex] will react with = [tex]\frac{2}{1}\times 2583.3=5166.4mol[/tex] of carbon
As the given amount of carbon is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.
Thus, [tex]SiO_2[/tex] is considered a limiting reagent because it limits the formation of the product.
For (a):By stoichiometry of the reaction:
1 mole of [tex]SiO_2[/tex] produces 1 mole of silicon
So, 2583.3 moles of [tex]SiO_2[/tex] will produce = [tex]\frac{1}{1}\times 2583.3=2583.3mol[/tex] of silicon
Since the molar mass of silicon = 28 g/mol
Putting values in equation 1:
[tex]\text{Mass of Si}=2583.3mol\times 28g/mol=72332.4g=72.33 kg[/tex]
Hence, the theoretical yield of silicon is 72.33 kg.
For (b):The percent yield of a reaction is calculated by using an equation:
[tex]\% \text{yield}=\frac{\text{Measured value}}{\text{Theoretical value}}\times 100[/tex] ......(2)
Given values:
Measured value of silicon = 66.0 kg
Theoretical value of silicon = 72.33 kg
Putting values in equation 1:
[tex]\% \text{yield}=\frac{66.0kg}{72.33kg}\times 100\\\\\% \text{yield}=91.25 \%[/tex]
Hence, the percent yield of the reaction is 91.25 %.
someone answer please
Answer:
A
Explanation:
Methanol and butanol are alcohols. Alcohols have the same_______________ as alkanes and the __________ identifies the compound as an alcohol.
Answer:
Methanol and butanol are alcohols. Alcohols have the same_______________ as alkanes and the __________ identifies the compound as an alcohol.
Explanation:
Alcohols belong to a group of organic compounds which contain -OH group as the functional group.
So alcohols have the same carbon -hydrogen bonds as alkanes and the -OH functional group identifies the compound as an alcohol.
The combination of isotopes of hydrogen characterized by emmision of radiation is believed to take place in the
a. sun
b. galaxy
c. moon
d. star
If the H3O is 4.950 x 10-12 what is the ph?
Answer:
pH = 11.3
Explanation:
From the question given above, the following data were obtained:
Concentration of hydronium ion [H₃O⁺] = 4.950×10¯¹² M
pH =.?
The pH of a solution is defined by the following equation:
pH = –Log [H₃O⁺]
Thus, with the above formula, we can obtain the pH of the solution as follow:
Concentration of hydronium ion [H₃O⁺] = 4.950×10¯¹² M
pH =.?
pH = –Log [H₃O⁺]
pH = –Log 4.950×10¯¹²
pH = 11.3
A mixture of sulfuric acid and nitric acid will produce small quantities of the nitronium ion (NO2 ): The nitronium ion has a central nitrogen atom with a positive charge double bonded to two oxygen atoms on both sides. Each oxygen atom carries two lone pairs of electrons. Does the nitronium ion have any significant resonance structures
Answer:
A mixture of sulfuric acid and nitric acid will produce small quantities of the nitronium ion (NO2 ): The nitronium ion has a central nitrogen atom with a positive charge double bonded to two oxygen atoms on both sides. Each oxygen atom carries two lone pairs of electrons. Does the nitronium ion have any significant resonance structures?
Explanation:
The structure of nitronium ion is shown below:
Any molecule to exhibit resonance, it should have alternating double bonds.
Resonance is the phenomenon in which the structure of a molecule can be represented in two or more forms and each form is called canonical form.
The canonical forms do not differ in the position of atoms and they differ only in the position of double bonds.
For the given molecule, there are no alternating double bonds.
Hence, nitronium ion does not exhibit any significant resonance structures.
Which two properties are explained by the pool-of-shared-electrons model for metals?
A. low vapor pressure, high melting point
B. malleability, conductivity
C. high melting point, conductivity
D. low vapor pressure, malleability
Answer:
Actually the answer is B Malleability, conductivity
Explanation:
What will be the pH change when 20.0 mL of 0.100 M NaOH is added to 80.0 mL of a buffer solution consisting of 0.163 M NH3 and 0.188 M NH4Cl
Answer:
[tex]pH=9.32[/tex]
Explanation:
Hello there!
In this case, according to the given scenario, it turns out necessary for us to realize that the addition of NaOH consumes the conjugate base, NH4Cl, and produces more base, NH3; that is why the reaction taking place is:
[tex]NH_4^++OH^-\rightarrow NH_3+H_2O[/tex]
Thus, the reacting moles of ammonium and hydroxide ions are:
[tex]n_{NH_4^+}=0.0800L*0.188mol/L=0.01504mol\\\\n_{OH^-}=0.0200L*0.100mol/L=0.00200mol[/tex]
Thus, the resulting moles of ammonium and ammonia are respectively:
[tex]n_{NH_4^+}=0.01504mol-0.00200mol=0.01304mol\\\\n_{OH^-}=0.0800L*0.163mol/L+0.00200mol=0.01504mol[/tex]
Then, by using the Henderson-Hasselbach equation and recalling the pKb of ammonia (4.74), we first calculate the pOH as follows:
[tex]pOH=pKb+log(\frac{n_{NH_4^+}}{n_{NH_3}} )\\\\pOH=4.74+log(\frac{0.01304mol}{0.01504mol} )\\\\pOH=4.68[/tex]
And finally the pH:
[tex]pH=14-4.68\\\\pH=9.32[/tex]
Regards!
A bag of gumdrops contains 17 orange gumdrops, 10 yellow gumdrops, and 18 black gumdrops.
What is the percent of yellow gumdrops?
Express your answer to two significant figures and include the appropriate units.
Answer:
Total number of gum drops = 10 + 17 +18
= 45
Explanation:
[tex] \frac{10}{45} \times 100 \\ = 22.222222\ \ \% \\ 22\% \: gum \: drops \: \\ to \: 2 \: sf[/tex]
How do I balance this?
_CuC12 + _NaNO3 → _CU(NO3)2 + _ NaC1
[tex]CuCl_2+2NaNO_3 \rightarrow Cu(NO_3)_2 + 2NaCl[/tex]
what is the molality of a solution that has 4 mol of KCI in 0.800 kg of water?
help me pleaseeee
The molality of a solution that has 4 mol of KCI in 0.800 kg of water is 4 mol/ 0.800 kg.
Therefore option B is correct.
What is molality?b is described as a measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent.
In order to calculate molality, we need to divide the number of moles of solute by the mass of the solvent in kilograms.
Molality = Number of moles of solute / Mass of solvent in kilograms
Molality = 4 mol / 0.800 kg
In conclusion, the molality is described as a measure of the concentration of a solution expressed in terms of the number of moles of solute per kilogram of solvent.
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9. The formular for finding the area
of an object is
A. Length + Width
B. Length - Width
C. Length : Width
D. Length x Width
E. 2 (Length + Width)
ans
Answer:
D. length × width
Explanation:
eg. 30 cm(length) × 20cm(width) = 600cm²
"A space shuttle travels around the Earth at a constant speed of 28000 kilometers per hour. If it takes 90 minutes to complete one orbit, how far is its journey around Earth?
"
Answer:
42000km
Explanation:
Average Speed (v) can be calculated using the formula as follows:
Average speed = distance (d) ÷ time (t)
According to this question, a space shuttle travels around the Earth at a constant speed of 28000 km/hr in 90 minutes.
Since 60 minutes = 1 hr
90 minutes = 90/60
= 3/2 or 1.5hours.
Using speed = distance/time
Distance (km) = speed × time
Distance = 28000 km/hr × 1.5hr
Distance = 42000km
which of the following illustrates a reversible change a cooking corn be rusting c frying egg and the boiling water
what is the importance of energy in humans
Explanation:
Energy is essential to life and all living organisms. The sun, directly or indirectly, is the source of all the energy available on Earth. Our energy choices and decisions impact Earth's natural systems in ways we may not be aware of, so it is essential that we choose our energy sources carefully
Identify whether longhand notation or noble-gas notation was used in each case below.
Answer:
The given electronic configuration is long hand notation.
Explanation:
Long-hand notation of representing electronic configuration is defined as the arrangement of total number of electrons that are present in an element.
Noble-gas notation of representing electronic configuration is defined as the arrangement of valence electrons in the element. The core electrons are represented as the previous noble gas of the element that is considered.
The given electronic configuration of potassium (K):
The above configuration has all the electrons that are contained in the nucleus of an element. Thus, this configuration is a long-hand notation.
What property can be easily measured in solids, liquids, and gases? (2 points)
Group of answer choices
The temperature of solids, liquids, and gases can be easily measured.
The texture of solids, liquids, and gases can be easily measured.
The color of solids, liquids, and gases can be easily observed.
The texture and temperature can be easily measured for solids, liquids, and gases.
Answer:
I think the answer is A
Explanation:
the temperature of solids , liquids and gases can be easily measured
Which of the following would eat a dead rabbit?
Herbivore
Carnivore
Omnivore
Detritivore
Please help
Detritivore
Explanation:
they eat the dead things
True or false? An organism may play more than one role in a food web
Answer:
true
Explanation:
because an organism have many roles in food web
explain how the solid liquid line in the phase diagram of water differs in character from the solid liquid line in the phase diagrams of most other substances such as CO2
Answer:
The solid-liquid line in the water phase diagram has a negative slope, whereas for most other substances it has a positive slope.
The ice has a lower density as compared to water still they have in the solid phase.
Reason how the solid-liquid line in the phase diagram as compared to other:In the solid-liquid line in the water phase diagram it contains the negative slope. While the most other substance should have the positive slope.
Also, when the pressure is applied so the higher density should be favored. In the water, the highest density phase should be likely the liquid water.
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54.56 g of water at 80.4 oC is added to a calorimeter that contains 47.24 g of water at 40 oC. If the final temperature of the system is 59.4 oC, what is the calorimeter constant (C calorimeter)
Answer:
49.5J/°C
Explanation:
The hot water lost some energy that is gained for cold water and the calorimeter.
The equation is:
Q(Hot water) = Q(Cold water) + Q(Calorimeter)
Where:
Q(Hot water) = S*m*ΔT = 4.184J/g°C*54.56g*(80.4°C-59.4°C) = 4794J
Q(Cold water) = S*m*ΔT = 4.184J/g°C*47.24g*(59.4°C-40°C) = 3834J
That means the heat gained by the calorimeter is
Q(Calorimeter) = 4794J - 3834J = 960J
The calorimeter constant is the heat gained per °C. The change in temperature of the calorimeter is:
59.4°C-40°C = 19.4°C
And calorimeter constant is:
960J/19.4°C =
49.5J/°C
how to calculate moles
Explanation:
First you must calculate the number of moles in this solution, by rearranging the equation. No. Moles (mol) = Molarity (M) x Volume (L) = 0.5 x 2. = 1 mol.
For NaCl, the molar mass is 58.44 g/mol. Now we can use the rearranged equation. Mass (g) = No. Moles (mol) x Molar Mass (g/mol) = 1 x 58.44. = 58.44 g.
Answer:
Number of moles : Mass (g) ÷ relative atomic mass
propose a synthetic route for the synthesis of a named alkanal starting with ethyl formate and grignard reagent.
Answer:
See explanation and image attached
Explanation:
A Grignard reagent is an alkyl magnesium halide. If it reacts with ethyl formate, an intermediate is formed as shown.
This intermediate can undergo water hydrolysis to form a diol, ethanol and MgBrOH.
Oxidation of the diol obtained now yields the corresponding alkanal which in this case is ethanal.
The scheme of the reaction is shown in the image attached to this answer.
I need the answer please
Answer:
the answer is the first one
Na+
What is the mass in grams of 0.700 moles of water, H2O
Answer:
12.6
Explanation:
[tex]no \: of \: mole= \frac{mass}{molar \: mass} [/tex]
0.7=mass/(2+16)
Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, 12.6g is the mass in grams of 0.700 moles of water.
What is mole?The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number. The stoichiometry represents the number of moles.
Mathematically,
number of moles of water=given mass of water÷ molar mass of water
Molar mass of 1 mole of water= 18 g/mol
mass of water= ?
0.700 moles=moles of water
Substituting all the given values in the above equation, we get
0.700 moles=mass of water ÷ 18 g/mol
mass of water =12.6g
Therefore, 12.6g is the mass in grams of 0.700 moles of water.
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Cyclopropane is more reactive than most cycloalkanes. What factors lead to cyclopropane being less stable than the other cycloalkanes
Answer: The factor that lead to cyclopropane being less stable than the other cycloalkanes is the presence of a RING STRAIN.
Explanation:
In organic chemistry, the end carbon atoms of an open aliphatic chain can join together to form a closed system or ring to form cycloalkanes. Such compounds are known as cyclic compounds. Examples include cyclopropane, cyclobutane, cyclopentane and many among others.
Cyclopropane is less stable than other cycloalkanes mentioned above because of the presence of ring strain in its structural arrangement. The ring strain is the spatial orientation of atoms of the cycloalkane compounds which tend to give off a very high and non favourable energy. The release of heat energy which is stored in the bonds and molecules cause the ring to be UNSTABLE and REACTIVE.
The presence of the ring strain affects mainly the structures and the conformational function of the smaller cycloalkanes. cyclopropane, which is the smallest cycloalkane than the rest mentioned above, contains only 3 carbons with a small ring.
A sample of a gas at 15°C and 2.50 atm pressure has a volume of 4.5 L. The pressure is lowered to 0.85 atm and the volume decreases to 2.5 L. What is the final temperature of the gas in K.
[tex]P_{1} = \text{2.50 atm}[/tex]
[tex]T_{1} = 15^{\circ}\text{C + 273 = 288 K}[/tex]
[tex]V_{1} = \text{4.5 L}[/tex]
[tex]P_{2} = \text{0.85 atm}[/tex]
[tex]V_{2} = \text{2.5 L}[/tex]
Unknown:[tex]T_{2}[/tex]
Solution:[tex]\dfrac{P_{1}V_{1}}{T_{1}} = \dfrac{P_{2}V_{2}}{T_{2}}[/tex]
[tex]T_{2} = T_{1} \times \dfrac{P_{2}}{P_{1}} \times \dfrac{V_{2}}{V_{1}}[/tex]
[tex]T_{2} = \text{288 K} \times \dfrac{\text{0.85 atm}}{\text{2.50 atm}} \times \dfrac{\text{2.5 L}}{\text{4.5 L}}[/tex]
[tex]\boxed{T_{2} = \text{54.4 K}}[/tex]
[tex]\\[/tex]
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Describe the three freezing points. Is there a relationship between the amount of solute in the solution and the freezing temperature
Answer:
The three freezing points will all be slightly different. It is given that a water solution has a freezing point of zero degrees Celsius, so water would have a freezing temperature below that. Salt will lower the freezing point, the more that is added.
Explanation:
Scientist A produces 83.67 g KMnO4 while Scientist B produces 81.35 g KMnO4.
What is the percent yield for Scientist A?
What is the percent yield for Scientist B?
You must show all work to receive full credit.
The equation for the production of potassium permanganate is as follows:
2 MnO2 + 2 KOH + O2 → 2 KMnO4 + H2
Answer:
[tex]Y_A=92.1\%\\\\Y_B=89.6\%[/tex]
Explanation:
Hello there!
In this case, according to the given chemical equation for the reaction for the production of potassium permanganate, we can see a 2:2 mole ratio of this product to the starting manganese (II) oxide, which means, we can calculate the theoretical yield of the former via stoichiometry:
[tex]m_{KMnO_4}=50.0gMnO_2*\frac{1molMnO_2}{86.94gMnO_2}*\frac{2molKMnO_4}{2molMnO_2} *\frac{158.034gKMnO_4}{1molKMnO_4} \\\\m_{KMnO_4}=90.9gKMnO_4[/tex]
Now, we are able to compute the percent yields, by using the actual yield each scientist got:
[tex]Y_A=\frac{83.67g}{90.9g} *100\%=92.1\%\\\\Y_B=\frac{81.35g}{90.9g} *100\%=89.6\%[/tex]
Regards!