The option, B. Reduced friction means reduced heat transfer " is correct.
Answer:
Reduces friction means increased efficiency
Explanation:
Friction is known to decrease efficiency in machines. In redesigning the engine if the antique car, and the inclusion of oil to reduce friction in the engine, she aims to improve the efficiency of the engine.
Friction leads to lost work in mechanical systems. Friction accounts for the fact that the efficiency of an engine is never 100% since some of the input work is lost as friction.
Hence decreasing the friction improves the efficiency of the machine.
Question 1(Multiple Choice Worth 4 points) (04.05 LC) What is the oxidation number of manganese in MnO41−? +3 +4 +7 +8 Question 2(Multiple Choice Worth 4 points) (04.05 LC) Which of the following reactions could be used to power a battery because of the transfer of electrons? Pb22+ + 2Br− → PbBr CaCl2 + 2NaOH → Ca(OH)2 + 2NaCl KOH + HCl → KCl + H2O Zn + Cu2+ → Zn2+ + Cu Question 3(Multiple Choice Worth 4 points) (04.05 MC) Read the following chemical equation: 2Al + 3Br2 → 2AlBr3 Which statement best identifies and describes the oxidizing agent in the reaction? Al is the oxidizing agent because its oxidation number increases. Al is the oxidizing agent because its oxidation number decreases. Br2 is the oxidizing agent because its oxidation number increases. Br2 is the oxidizing agent because its oxidation number decreases. Question 4(Multiple Choice Worth 4 points) (04.05 MC) In which of the following reactions is chlorine (Cl) oxidized? Br2 + 2Cl− → Cl2 + 2Br− Cl2 + 2e− → 2Cl− 2ClO3− + 12H+ → Cl2 + 6H2O 2Na + Cl2 → 2NaCl Question 5(Multiple Choice Worth 4 points) (04.05 MC) The diagram shows the setup of an experiment. A few observations of the experiment are listed in the table below the diagram. A beaker filled three-fourths with a liquid labeled colorless silver nitrate solution is shown. A small strip is shown inside the beaker. The strip is labeled copper strip. The title of the image is Experimental Setup. Experimental Observations Observation Description 1 Solution turned blue 2 Gray particles were deposited on the edge of the strip Which of the following is the correct explanation for one of the given observations? Observation 2 is a result of nitrate ions moving into the solution. Observation 1 is a result of copper ions moving into the solution. Observation 1 is a result of silver atoms losing one electron. Observation 2 is a result of silver ions losing one electron.
1) Answer is: the oxidation number of manganese in MnO₄⁻ is +7.
Permanganate anion has negative charge 1-.
Oxygen (O) in permanganate anion has oxidation number -2.
x + 4 · (-2) = -1.
x - 8 = -1.
x = +7; oxidation nzmber of manganese.
Oxidation number shows the degree of oxidation of an atom in a chemical compound.
2) Answer is: Zn + Cu2+ → Zn2+ + Cu.
In this chemical reaction, there is transfer of electrons from zinc (Zn) to copper (Cu). Zinc change oxidation number from 0 to +2 (lost electrons) and copper change oxidation number from +2 to 0 (gain electrons).
Oxidation half reaction: Zn⁰ → Zn²⁺ + 2e⁻.
Reduction half reaction: Cu²⁺ + 2e⁻ → Cu⁰.
In other chemical reactions, there is no change of oxidation number of elements.
3) Answer is: Br2 is the oxidizing agent because its oxidation number decreases.
Balanced chemical reaction: 2Al + 3Br₂ → 2AlBr₃.
In this chemical reaction, aluminium change oxidation number from 0 to +3 (lose electrons) and bromine change oxidation number from 0 to -1 (gain electrons, reduced).
Oxidizing agent is a substance that has the ability to oxidize other substances, to cause them to lose electrons.
In oxido-reduction reaction, at least one element lose and one element gain electrons.
4) Answer is: Br2 + 2Cl− → Cl2 + 2Br⁻.
Oxidation is increase of oxidation number.
In this balanced chemical reaction, chlorine change oxidation number from -1 (Cl⁻) to oxidation number 0 (Cl₂).
Oxidation half reaction: 2Cl⁻ → Cl₂⁰ + 2e⁻.
Reduction half reaction: Br₂ + 2e⁻ → 2Br⁻.
In other chemical reactions, chlorine is reduced.
5) Answer is: Observation 1 is a result of copper ions moving into the solution.
The reactivity series is a series of metals from highest to lowest reactivity. Metal higher in the reactivity series will displace another.
Copper (Cu) is higher in activity series than silver (Ag), so copper lose electron and silver gain electrons.
Copper is oxidized (increase of oxidation number) and silver is reduced.
Answer:
There's no one-upping that one so I'll just tell you that they were right on my test :)
Explanation:
you're welcome
In an experiment, 0.6mol of chlorine gas, Cl2, is reacted with an excess of hot aqueous sodium hydroxide. One of the products is a compound of sodium, oxygen and chlorine. Which mass of this product is formed?
A 21.3 B 44.7 C 63.9 D 128
Answer: B) 44.7 g
Explanation:
The equation represent the reaction is
Cl2 + 2NaOH → NaCl + NaClO + H2O
The balanced equation shows that every mole of Cl2 reacts to produce mole of NaClO
0.6 mole of Cl2 will produce 0.6 mole of NaClO
n = mass/molar mass
molar mass of NaClO = 74.5 g/mol
the mass of NaClO = n x molar mass = (0.6 mole) (74.5 g/mol) = 44.7 g
The elements X and Y combine in different ratios to form four different types of compounds: XY, XY₂, XY₃, and XY₄. Consider that there is enough of each sample to contain 2 g of X, and the mass of X is estimated to be 2 g and the mass of Y is estimated to be 4 g.
Arrange the following ratios in order of their increasing value. (The exercise gives me three tabs to put in order from highest to least. These are in the pic)
Rank from highest to lowest ratio. To rank items as equivalent, overlap them.
I put XY₄ as highest, then XY₃ in the middle, and XY₂ as lowest. Is this order correct? I'm not quite understanding this lesson :// so if i could also get some sort of an explanation, that'd be great!!
Yeah, it would be that order since if XY was a number, you would multiply it by that number 4 total times. So it would be a large number. And then it gets smaller and smaller when it gets to XY2. So yeah you got the order correct.
Elements are species of atoms that are defined and characterized by the number of protons. The multiple proportions of the element from higher to lowest are XY₄, XY₃, and XY₂.
What are elements?Elements have been defined as the atomic species that make the molecule and the compounds by combining chemically through bond formation. They are indivisible particles that cannot be broken further.
When two or more elements chemically links then a compound or molecule is formed like element X and Y combined in various ratios and proportions to form XY, XY₂, XY₃, and XY₄.
The highest ratio of the proportions will be XY₄ as it has one X and four Y elements, followed by XY₃ with one X and three Y. Lastly XY₂ will be the lowest ratio as it has one X and two Y elements.
Therefore, the order is XY₄> XY₃ > XY₂.
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Hydrogen gas can be made by reacting methane (CH4) with high temperature steam: CH4(g) + H2O(g) ---> CO(g) + 3H2(g)
How many hydrogen molecules are produced when 256 grams of methane reacts with steam? Please SHOW WORK so I can understand the concept
CH4(g) + H2O(g) ---> CO(g) + 3H2(g)
mass of methane CH4 = 256g
molar mass of methane,CH4 = C + 4 H = 16.04g/mol
moles of CH4
= mass/Molar mass
= 256/16.04
= 15.96 moles CH4
moles of H2 produced
= 15.96 moles CH4 x 3 moles H2
1 mol CH4
= 47.88 moles H2
number of H2 molecules produced here
= 47.88 moles H2 x 6.022 x 10²³ molecules
1 mole
= 288.335 x 10²³ H2 molecules
= 2.88 x 10²⁵ H2 molecules
2.88 x 10²⁵ H2 molecules are produced when 256g of methane reacts with steam.
A 1.00 g sample of a hydrogen peroxide (H2O2) solution is placed in an Erlenmeyer flask and diluted with 20 mL of 1 M aqueous sulfuric acid. To this solution is added 0.0200 M KMnO4 solution via a buret, until a pale purple color persists. This requires 22.50 mL of KMnO4 solution. What is the percent by mass of hydrogen peroxide in the original solution? (A) 0.613% (B) 1.53% (C) 3.83% (D) 7.65%
Place the items in order from the largest wavelength to the shortest wavelength.
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Blue visible
Gamma radiation
Green visible
Infrared
Microwave
Orange visible
Radio wave
Red visible
Ultraviolet (UV)
Violet visible
X-ray
Yellow visible
The order from longest to shortest wavelength is;
Radio wave (longest wavelength)
Microwave
Infrared
Red visible
Orange visible
Yellow visible
Green visible
Blue visible
Violet visible
Ultraviolet (UV)
X-ray
Gamma radiation (shortest wavelengths)
This is referred to as the electromagnetic spectrum.
The EM radiation types ordered from largest to shortest wavelength are: Radio wave, Microwave, Infrared, Red visible, Orange visible, Yellow visible, Green visible, Blue visible, Violet visible, Ultraviolet (UV), X-ray, and Gamma radiation.
To place the various types of electromagnetic (EM) radiation in order from largest wavelength to shortest wavelength, we'll refer to the relationship between wavelength, frequency, and energy of EM waves. As the wavelength decreases, both the frequency and energy increase. Here's the correct order from largest to shortest wavelength:
Radio waveMicrowaveInfraredRed visibleOrange visibleYellow visibleGreen visibleBlue visibleViolet visibleUltraviolet (UV)X-rayGamma radiationWithin the visible light spectrum, remember ROY G BIV as a mnemonic to order the colors from longest (red) to shortest (violet) wavelengths. Beyond the visible spectrum, infrared radiation has longer wavelengths than visible red light, whereas ultraviolet light, X-rays, and gamma rays have shorter wavelengths than visible violet light.
When Mrs. Green describes the physical properties of matter she said that physical properties often concern changes in state. One physical property that does not describe a change in state is
Some physical properties of matter do not involve a change in state. An example is density, which is an intensive property that does not depend on the amount of matter. It remains consistent regardless of the state of the substance.
Explanation:Physical properties of matter are characteristics that can be observed without changing the chemical composition of the substance. These properties can often describe changes in state, such as from a solid to a liquid (melting) or a liquid to a gas (boiling). However, there are also other types of physical properties that do not involve a change in state.
One of these physical properties is density. Density does not involve a change in the state of a substance. It is an intensive property, meaning it does not depend on the amount of matter present. It is determined by the mass of an object divided by its volume, and it remains the same regardless of the quantity of the substance you have.
Therefore, Mrs. Green could have been referring to a property like density when she mentioned a physical property that does not describe a change in state.
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Physical properties are characteristics of matter that don't involve a change in the composition of matter. One example is density, which isn't tied to a change of state. Other physical properties include hardness, color, smell, boiling point, and solubility.
Explanation:When Mrs. Green discusses the physical properties of matter, she is referring to characteristics of matter that are not associated with any change in its chemical composition. Physical properties, such as hardness and boiling point, do not involve a change in the composition of matter, hence they do not correspond to a change of state. An example is the density of a material which remains the same regardless of its state (solid, liquid, or gas). Density is therefore a physical property that does not describe a change in state. Other examples can include color, smell, freezing point, boiling point, and solubility.
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