Answer:
A
Explanation:
In this question, we are to calculate the enthalpy of change of the reaction. ΔH
To be able to do that, we use the Hess’ law and it involves the subtraction of the summed heat reaction of the reactants from that of the product.
Thus, mathematically, the enthalpy of change of the reaction would be;
[ΔH(CCl4) + 4 ΔH(HCl)] - [ΔH(CH4) + 4 ΔH(Cl2)]
We can see that we multiplied some heat change by some numbers. This is corresponding to the number of moles of that compound in question in the reaction.
Also, for diatomic gases such as chlorine in the reaction above, the heat of reaction is zero.
Thus, we can have the modified equation as follows;
[ΔH(CCl4) + 4 ΔH(HCl)] - [ΔH(CH4)]
Substituting the values we have according to the question, we have;
-95.98 + 4(-92.3) -(-17.9)
= -95.98 - 369.2 + 17.9
= -447.28 KJ/mol
Which answer best describes what is happening in the following redox reaction?
4Fe + 302.
2Fe2O3
Answer:
Iron is oxidized to form rust.
Explanation:
Consider the reaction; 4Fe + 302------>2Fe2O3, we can see that iron is being oxidized to iron III oxide. Rust is the common name of iron III oxide.
Rusting is an electrochemical process, iron rusts when it comes into contact with air and water because electrochemical cells are set up at the surface of contact.
Iron usually functions as the anode in the electrochemical process. This process leads to the formation of iron III oxide. Rust is soft and breaks off easily thereby exposing the metal below the surface to further rusting.
Answer:
Iron is oxidized to form rust.
Explanation:
edge
Choose the correct answer:
In a galvanic cell:
a- The reactions taking place are non spontaneous
b- The cathode is negative
c- Electrical energy is converted into chemical energy
d- Chemical energy is converted into electrical energy
Answer:
D.
Explanation:
In a Galvanic cell:
1) Spontaneous reactions take place
2) Chemical Energy is converted to some useful electrical energy
What causes the sea floor to move apart at a sea floor spreading center A density B continental drift C paleomagnetism D convection currents
Answer: D convection currents
Explanation:
The seafloor spreading is a phenomena that occurs due to liberation of heat from the convection currents generated in the mantle. It makes the earth crust more plastic and less dense. This happens at divergent plate boundaries. As the plates move apart, the less denser material rises. It leads to the formation of mountain and crust cracks.
A certain volume of a gas had a pressure of 800 torr at a temperature of -40 degrees C. What was the original volume if the volume at STP is now 450.0 cm^3?
(the correct answer is 365 cm^3. I just need an explanation.)
Answer : The original volume of gas is [tex]365cm^3[/tex]
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 = 800 torr
[tex]P_2[/tex] = final pressure of gas at STP = 760 torr
[tex]V_1[/tex] = initial volume of gas = ?
[tex]V_2[/tex] = final volume of gas at STP = [tex]450.0cm^3[/tex]
[tex]T_1[/tex] = initial temperature of gas = [tex]-40^oC=273+(-40) =233K[/tex]
[tex]T_2[/tex] = final temperature of gas at STP = [tex]0^oC=273+0=273K[/tex]
Now put all the given values in the above equation, we get:
[tex]\frac{800torr\times V_1}{233K}=\frac{760torr\times 450.0cm^3}{273K}[/tex]
[tex]V_1= 364.8cm^3\approx 365cm^3[/tex]
Therefore, the original volume of gas is [tex]365cm^3[/tex]
sperm can be carried by _____ grains. ANSWERSSSSSSSSSSSSSSSSS O spore O stamen O pollen
What is pollen in the reproduction cycle of flowering plants?
A pollen grain is a microspore containing the male gametophyte, usually reduced to two undivided cells, each with one haploid (n) nucleus. These cells are surrounded by a very resistant wall, the exine, which generally has apertures, zones with less resistance which will allow the germination of the pollen tube.
Explanation of the reproduction cycle (cf diagram above)
A given species produces flowers bearing stamens. According to species, these flowers can be unisexual (stamens only) or bisexual (stamens and carpels).
The stamen anthers include 4 pollen sacs containing sporogenous cells (diploid=2n). These sporogenous cells undergo meiosis, each producing 4 microspores (haploid=n). Two nuclei are then formed by mitosis : the vegetative nucleus and the generative nucleus. The latter divides to form 2 sperms. Simultaneously the wall of the microspores becomes thicker and takes the characteristic shape of the species : it is a pollen grain (see: What are the morphological characteristics of pollen and spore grains?). In the majority of species, the 4 grains (resulting from the 4 microspores) split up into single grains; in some cases, they remain together (tetrad = group of 4 grains). When mature, pollen grains are released by the opening of the anthers.
A pollen grain is aimed at reaching another flower of the same species, bearing carpels. The ovaries contain ovules, in which meiosis occurs, then mitoses. It results in an embryo sac with 8 nuclei, among which an egg cell and 2 central cells. When a pollen grain arrives on another flower (see : How are the spores and pollen grains transported?), it is received by the stigmas.
The pollen grain germinates through an opening of the wall: the vegetative nucleus develops into a pollen tube which is guided by the style to the ovary, then enters the micropyle of an ovule. The pollen tube releases 2 sperm nuclei into the ovule: one of the sperms fuses with the egg cell into a zygote (2n), while the other sperm fuses with central nuclei and gives rise to albumen (= food source). There are generally several ovules in an ovary : each one can be fertilized by a distinct pollen grain.
Each fertilized ovule and its albumen form a seed that will develop into a new individual of this species. hope it works
Answer:
pollen
Explanation:
you insolent vacuum
Formation of heat and/or light when two substances are combined indicate a _______ change.
Answer:
It's a chemical change
Pls help asap!!! I don’t understand how to do it
Answer:
split the reaction in to respective ions to ge the ionic equation of this reaction
Explanation:
2 Al + 2Fe+3 O3^-2 ---> 2Al+3 O3^-2 + 2Fe
ins simple it would be
Al + Fe+3 ----> Al+3 + Fe
Mass box A = 10 grams; Mass box B = 5 grams; Mass box C—made of one A and one B
How many boxes of A would be required to make 30 grams of C?
Answer:
the answer would be 2
Explanation:
Wildflowers bloom earlier than large trees. This helps wildflowers compete for _____. water, light, food, or air
Answer: Light
Explanation:
The environment abiotic factors like sunlight, water, air, and soil are important for the growth of the plants. A wildflowers is a plant that grows in wild. It was not intentionally seeded or planted.
The light is one of the important environmental factor. As the wildflowers are blooming earlier than the large trees. Thus the wildflowers are receiving the light earlier than large trees.
What did early scientists assume that the polar caps had in common?
Answer:
They assumed they both had water.
Explanation:
Because they only could look at it through telescopes that were not advanced
what happens when sodium and sulfur combine
Answer:
Sodium sulfide is the chemical compound with the formula Na2S, or more commonly its hydrate Na2S·9H2O. Both the anhydrous and the hydrated salts are colorless solids. They are water-soluble, giving strongly alkaline solutions. When exposed to moist air, Na2S and its hydrates emit hydrogen sulfide, which smells like rotten eggs. Some commercial samples are specified as Na2S·xH2O, where a weight percentage of Na2S is specified. Commonly available grades have around 60% Na2S by weight, which means that x is around 3. Such technical grades of sodium sulfide have a yellow appearance owing to the presence of polysulfides. These grades of sodium sulfide are marketed as 'sodium sulfide flakes'.
Contents
1 Structure
2 Production
3 Reactions with inorganic reagents
4 Uses
4.1 Reagent in organic chemistry
5 Safety
6 References
Structure
Na2S adopts the antifluorite structure,[2][3] which means that the Na+ centers occupy sites of the fluoride in the CaF2 framework, and the larger S2− occupy the sites for Ca2+.
Production
Industrially Na2S is produced by carbothermic reduction of sodium sulfate often using coal:[4]
Na2SO4 + 2 C → Na2S + 2 CO2
In the laboratory, the salt can be prepared by reduction of sulfur with sodium in anhydrous ammonia, or by sodium in dry THF with a catalytic amount of naphthalene (forming sodium naphthalenide):[5]
2 Na + S → Na2S
Reactions with inorganic reagents
The sulfide ion in sulfide salts such as sodium sulfide can incorporate a proton into the salt by protonation:
S2−
+ H+ → SH−
Because of this capture of the proton ( H+), sodium sulfide has basic character. Sodium sulfide is strongly basic, able to absorb two protons. Its conjugate acid is sodium hydrosulfide (SH−
). An aqueous solution contains a significant portion of sulfide ions that are singly protonated.
S2−
+ H
2O {\displaystyle {\ce {<=>>}}}{\displaystyle {\ce {<=>>}}} SH−
+ OH−
(1)
SH−
+ H
2O {\displaystyle {\ce {<<=>}}}{\displaystyle {\ce {<<=>}}} H
2S + OH−
(2)
Sodium sulfide is unstable in the presence of water due to the gradual loss of hydrogen sulfide into the atmosphere.
When heated with oxygen and carbon dioxide, sodium sulfide can oxidize to sodium carbonate and sulfur dioxide:
2 Na2S + 3 O2 + 2 CO
2 → 2 Na2CO3 + 2 SO2
Oxidation with hydrogen peroxide gives sodium sulfate:[6]
Na2S + 4 H2O2 → 4 H
2O + Na2SO4
Upon treatment with sulfur, polysulfides are formed:
2 Na2S + S8 → 2 Na2S5
Uses
Sodium sulfide is primarily used in the kraft process in the pulp and paper industry.
It is used in water treatment as an oxygen scavenger agent and also as a metals precipitant; in chemical photography for toning black and white photographs; in the textile industry as a bleaching agent, for desulfurising and as a dechlorinating agent; and in the leather trade for the sulfitisation of tanning extracts. It is used in chemical manufacturing as a sulfonation and sulfomethylation agent. It is used in the production of rubber chemicals, sulfur dyes and other chemical compounds. It is used in other applications including ore flotation, oil recovery, making dyes, and detergent. It is also used during leather processing, as an unhairing agent in the liming operation.
Reagent in organic chemistry
Alkylation of sodium sulfide give thioethers:
Na2S + 2 RX → R2S + 2 NaX
Even aryl halides participate in this reaction.[7] By a broadly similar process sodium sulfide can react with alkenes in the thiol-ene reaction to give thioethers. Sodium sulfide can be used as nucleophile in Sandmeyer type reactions.[8] Sodium sulfide reduces1,3-dinitrobenzene derivatives to the 3-nitroanilines.[9] Aqueous solution of sodium sulfide can be refluxed with nitro carrying azo dyes dissolved in dioxane and ethanol to selectively reduce the nitro groups to amine; while other reducible groups, e.g. azo group, remain intact.[10] Sulfide has also been employed in photocatalytic applications.[11]
Explanation:there you go
When sodium combines with sulphur, it formed sodium sulphide. When it interacts with sulfur, polysulfides are produced. Additionally, heat causes sodium sulfide to oxidize fast. Sulfur dioxide and sodium carbonate are the end products.
What is sulphur ?Chemical element sulfur has the letter S and atomic number 16. It is multivalent, nonmetallic, and plentiful. Sulfur atoms normally combine to create cyclic octatomic molecules, which have the chemical formula S₈.
At room temperature, elemental sulfur is a crystalline solid that is brilliant yellow. It is employed in the production of fertilizer, water treatment, mineral extraction, oil refining, and automobile batteries.
Other uses for compounds based on sulfur include vulcanizing rubber, bleaching paper, and producing goods like cement, detergents, and insecticides.
Thus, When sodium combines with sulphur, it formed sodium sulphide.
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what is genetic tagging
Answer:
Genetic tagging, or the identification and tracking of individual animals using DNA, is a non-invasive method of conducting research that uses samples from shed hair, feathers, feces, or saliva. ... Genetic tagging approaches are complementary to traditional approaches and add a powerful tool to the ecologists' toolkit."
Explanation:
Predict the arrangement of the following substances in decreasing order of pH value Orange juice || Bitter gourd juice || Hydrochloric acid || Mineral water
Answer:
Mineral water> Bitter gourd juice> Orange juice> Hydrochloric acid
Explanation:
pH is referred to as the degree of acidity or alkalinity of a substance. The pH scale is arranged from 0-14. Substance with a pH of 0-6.9 are acid, a pH of 7 indicates neutrality while a pH of 8-14 indicates alkalinity.
Mineral water is usually slightly acidic with a pH between 5-6. The pH of bitter gourd juice is between 4.24-4.45. The pH of orange juice ranges between 3.3 to 4.2 lastly, the pH of hydrochloric acid is about 3.01.
The pH values itemized above informed the arrangement of decreasing pH values shown in the answer box.
This chemical equation is balanced.
F2+ 2NaBr – 2NaF + Br2
How does the balanced chemical equation show the conservation of matter
in this chemical reaction?
O A. The number of Fatoms in the reactants equals the number of F
atoms in the products.
B. There are more Br atoms in the reactants than in the products.
C. There are fewer Na atoms in the reactants than in the products.
D. The compound Naf is a substance that is different from the
compound NaBr
Answer:
A
Explanation:
1. Hummingbirds eat approximately 43.0 g of sugar water per day How many moles of carbon dioxide are released daily by a hummingbird's respiration? C_12H_22O_11 + 12O_2 ------> 12CO_2 + 11H_2O
Answer:
1.507 moles of CO₂ are released daily by a hummingbird's respiration
Explanation:
The reaction of production of carbon dioxide and water from sugar is:
C₁₂H₂₂O₁₁ + 12O₂ → 12CO₂ + 11H₂O
Where 1 mole of sugar produce 12 moles of CO₂
Molar mass of sugar (To convert the mass to moles) is:
12C = 12ₓ12.01g/mol = 144.12g/mol
22H = 22ₓ1.01g/mol = 22.22g/mol
11O = 11ₓ16g/mol = 176g/mol
144.12 + 22.22 + 176 = 342.34g/mol
Thus, moles of 43.0g of sugar are:
43.0g ₓ (1mol / 342.34g) = 0.1256 moles of sugar.
As 1 mole of sugar produce 12 moles of CO₂:
0.1256 moles of sugar ₓ (12 moles CO₂ / 1 mol sugar) =
1.507 moles of CO₂ are released daily by a hummingbird's respiration
What is the correct order of processes in the accretion of planetesimals?
Answer:
A). Collapse, condensation, accretion, clearing.
Explanation:
Planetesimals are described as the small solid astronomical objects which are the building blocks for the formation of solid planets. Accretion is described as the process in which the solid astronomical objects cluster to form larger objects that eventually leads to the formation of planets.
As per the question, the correct order of processes that are followed in this accretion process would be a collapse, condensation, accretion, clearing. First occurs the collapse of a nebula followed by condensation of cosmic dust grains. After this, the accession or accumulation of solid parts takes place to form larger objects and this is immediately followed by the clearing of debris and dust to allow planets to form. Thus, option A is the correct answer.
Answer:
a
Explanation:
Which reaction does not involve neutralization? A. H 2 SO 4 + 2NH 3 -------> (NH 4 ) 2 SO 4 B. H 2 SO 4 + BaCl 2 --------> BaSO 4 + 2HCl C. H 2 SO 4 + CuO -----> CuSO 4 + H 2 O D. H 2 SO 4 + 2NaOH ----> Na 2 SO 4 + 2H 2 O
Answer:
B. H2SO4 + BaCl 2 --------> BaSO4 + 2HCl
Explanation:
Neutralization reactions are characterized by their reactants of acids and bases reacting to form salt and water. All of the options except B, have formation of salt and water. Also, B is more likely a percipitation reaction (also a double displacement reaction) and not neutralization.
If the frequency of a wave is 68 hertz then the period of the wave is going to be
Answer:
0.01471 seconds
Explanation:
the period of a wave is given by 1/frequency.
Consider the word equation.
calcium hydroxide + hydrochloric acid → calcium chloride + water
Which is the corresponding formula equation?
A: CaCl2(1)→ Ca(s) + Cl2(g)
B: O CaO(s)+ H2O(1)>Ca(OH)2(aq)
C: NaOH(aq) + 2HCl(aq) → NaCl(aq) + 2H2O(1)
D: Ca(OH)2(S) + 2HCI(I) → CaCl2(aq) + 2H20(1)
The chemical equation for the given word equation is Ca(OH)[tex]_2[/tex](S) + 2HCI(I) → CaCl[tex]_2[/tex](aq) + 2H[tex]_2[/tex]0(1). Therefore, the correct option is option D.
Chemical equations are symbols or chemical formulas that depict a chemical reaction symbolically. With a plus sign separating the entities in the reactants and products, the reactant objects are listed on the left as well as the result entities are listed on the right.
An arrow indicating the reaction's direction points in the path of the products. The chemical formulas could be mixed, symbolic, or structural. The critical values of a stoichiometric figures are shown as coefficients beside the symbols as well as formulas of the various entities. The chemical equation for the given word equation is Ca(OH)[tex]_2[/tex](S) + 2HCI(I) → CaCl[tex]_2[/tex](aq) + 2H[tex]_2[/tex]0(1).
Therefore, the correct option is option D.
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Which claim about cats is most likely based on science?
O A. Egyptian myths explain that the sun god, Ra, appeared in living
form as a cat.
O B. Fairy tales during the Middle Ages said that cats are evil and that
they spread plague.
C. Ancient Eastern cultures believed that cats should be held in high
regard.
D. Genetic data show that modern domestic cats are related to Near
Eastern wildcats.
Answer:D
Explanation:
The claim about cats is most likely based on science is Genetic data show that modern domestic cats are related to Near Eastern wildcats. The correct option is D.
What is a claim?A claim is a statement that is given by a person about his or her things, and they claim that the thing. It gives proof that a thing or house is a person's property.
Genetic data is the data of the genetic sequence of a person's genetic information. It is different for every person. So genetic data is very important.
So the scientific data will be the genetic data of cats that is claiming that domestic cats are related to Near Eastern wildcats. It is most likely a scientific claim.
Thus, the correct option is D. Genetic data show that modern domestic cats are related to Near Eastern wildcats.
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Why do reactions need to be balanced?
A. Because the reactants must be the exact same as the products
B. Because of the conservation of energy
C. Because the volume of reactants must equal the volume of
products
D. Because atoms are not lost or gained in a chemical reaction
Answer:
A part.
Explanation:
Because the reactants must be the exact same as the the products.
Complete the following ionic equation: [tex]Zn + 2Ag^{+} ---\ \textgreater \ ......... + ..........[/tex]
Answer: [tex]Zn+2Ag^+\rightarrow Zn^{2+}+2Ag[/tex]
Explanation:
Oxidation-reduction reaction or redox reaction is defined as the reaction in which oxidation and reduction reactions occur simultaneously and the number of electrons lost is equal to the number of electrons gained.
Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.
Anode : [tex]Zn\rightarrow Zn^{2+}+2e^-[/tex]
Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.
Cathode : [tex]2Ag^++2e^-\rightarrow 2Ag[/tex]
Thus the complete ionic equation will be :
[tex]Zn+2Ag^+\rightarrow Zn^{2+}+2Ag[/tex]
the temperature of a sample of water increases from 20celsius to 46.6celsius as it absorbs 5650 J of heat. what is the mass of the sample?
Answer:
m = 50.74 kg
Explanation:
We have,
Initial temperature of water is 20 degrees Celsius
Final temperature of water is 46.6 degrees Celsius
Heat absorbed is 5650 J
It is required to find the mass of the sample. The heat absorbed is given by the formula ad follows :
[tex]Q=mc\Delta T[/tex]
c is specific heat of water, c = 4.186 J/g°C
So,
[tex]m=\dfrac{Q}{c\Delta T}\\\\m=\dfrac{5650}{4.186\times (46.6-20)}\\\\m=50.74\ kg[/tex]
So, the mass of the sample is 50.74 kg.
What is the pH of a 0.45 M solution of hydrochloric acid
pH = 0.35
Explanation: hope this helps
Answer: 0.35
Explanation:
write the structure of 2 butene class 10
Answer:
The answer is C4H8.
Explanation:
I hope it helps you
Pass your test fast okay
BYE!
1. Which of these show a diatomic element?
CO
H₂
He
SO₂
2. Which of these substances is an element?
Chlorine
Ice
Methane
Sodium chloride
3. When the elements lead and bromine combine together, the name of the substance formed is called .......
Lead bromate
Lead bromide
Lead bromite
Lead bromium
Answer:
1) H2
2) Chlorine
3) Lead bromide
What is the molar mass of sulfur trioxide?
Answer:
80.07 g/mol
Explanation:
Sulfur's g/mol = 32.07
Oxygen's g/mol = 16.00
32.07 + 16.00(3) = 80.07 g/mol
Answer:
80.07 g/mol
Explanation:
16. State one advantage and disadvantage
of rusting
Answer:
Advantage:
It forms ferrous oxide which is used as a pigment for glasses
Disadvantage:
It destroys the appearance of the metal and weakens it.
Answer:
Advantage: Rusting provides a thin durable shell to prevent the metal from getting more corroded.
Disadvantage: Rusting weakens material due to prolonged corrosive action.
Explanation:
Mendeleev's periodic table of elements was created in 1901.
O A. True
O B. False
Explanation:APΕX
If 0.360 J of heat is added to 0.7402 g of water, how much will the temperature increase?
Answer:
You are not supposed t9 be cheating
Explanation:
Answer:
ΔT = 0.116 °C
Explanation:
Using Formula
Q = mc ΔT
Where Q = 0.360, c = 4.184 and m = 0.7402
ΔT = Q/mc
ΔT = 0.360/ (4.184)(0.7402)
ΔT = 0.360 / 3.097
ΔT = 0.116 °C
So, The change in Temperature/Increase in Temperature is 0.116 °C