A group of students were asked to design a device that converts light energy into heat. They built a small solar oven using a tin can and aluminum foil. The device reflects light into the can, warming up its contents.
Which action would most improve the design of the solar oven?
O A. Add a mirror to reflect light away from the can.
O B. Use hand lenses to focus the light into the can.
O c. Add a fan to make sure the food is evenly warmed.
O D. Change the tin can to a box with a lid to Increase cooking space.
Answer:
answer is b
Explanation:
I think it is b. I don't know what land lenses are but focusing light on the can would heat it up more.
In a physical change, the makeup of matter is changed.
True or false?
Answer:
false
Explanation:
because it's just a physical change, the matter won't be changed.
Hope this might help you! I don't know if this is going to be right on everything, but it's a anwser
In a physical change, the makeup of matter is changed. This statement is false.
What do you mean by the term physical change ?
A physical change occurs when a substance experiences a change in its physical characteristics. A physical alteration may usually be reversed. No new material is produced with such a transformation.
As the substance's composition changes, a chemical reaction takes place. A chemical change happens when bonds are broken and new ones are created.
Physical change is a sort of change when the substance's chemical makeup does not change. Often, this type of alteration entails a change in the substance's size, form, and condition.
Thus, In a physical change, the makeup of matter is not changed because it's a physical change.
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Different isotopes of an element have different numbers of:
Explanation:
Different isotopes of an element have different numbers of mass number
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Select the correct answer.
In which situation is chemical energy being converted to another form of energy?
A.
a lamp plugged into the electric grid
B.
a fluttering flag
C.
a floating wooden log
D.
a burning candle
How many moles is 2.50 grams of oxygen?
Answer:
Mole is a number that connects mass of a substance with its number of particles. 2500 g of O2 = 1/32 x 2500 = 78.125 moles
Explanation:
have a great day
Is mercury an electrolyte at room temperature?
Answer:
No
Explanation:
Despite mercury being a metal, it is a liquid at room temperature. It cannot be an electrolyte. This is because most of the liquids that can conduct electricity or acids bases and salts whereas mercury is a metal.
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HC= Hydrocarbon
CH=benzene
Explanation:
HC is Hydrocarbon, how? -- Hydrocarbon, a category of substances consisting only of hydrogen and carbon.
CH is benzene, how? -- benzene is represented by the empirical formula CH, which indicates that a typical sample of the compound contains one atom of carbon (C) to one atom of hydrogen (H).
----(Is this what you meant???)
1. Which of the following statements about the properties of elements related to an
atomic emission spectrum are true? Select all that apply. (3 are correct)
The emission spectrum of an atom consists of limited lines that are unique to a given element.
According to the Bohr model of the atom, energy is absorbed or emitted when an atom moves from one energy level to another. Since energy is quantized, the spectrum of atoms often consists of single lines.
Hence, the true statement about atomic spectrum is that; "the light that an element emits is made up of a limited number of narrow lines that produce a unique pattern or atomic emissions spectrum for that element."
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What is the enthalpy of reaction for the decomposition of calcium carbonate? CaCO3(s) Right arrow. CaO(s) CO2(g) kJ.
The enthalpy of reaction for the decomposition of calcium carbonate is 177.4 KJ/mole .
We know that the enthalpy of reaction can be obtained from the enthalpy of formation of the reactants and that of the products using the formula;
ΔHrxn = ΔHf (products) - ΔHf (reactants)
The heat of formation of the species are as follows;
ΔHf (CaCO3(s)) = −1206.9 KJ/mol
ΔHf (CaO(s)) = - 636 KJ/mole
ΔHf (CO2(g)) = -393.5 KJ/mole
ΔHrxn = [( -393.5 KJ/mole ) + ( - 636 KJ/mole)] - [ −1206.9 KJ/mol]
ΔHrxn = 177.4 KJ/mole
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Answer:
First one is 656.3 and second is endothermic.
Explanation:
Edge Thermochemical Equations assignment
HELP PLSS ASAP PLEASE
Answer:
5.24 x 10^23
Explanation:
Avogadro's constant is 6.02 x 10^23
1 mol = 6.02 x 10^23
0.87 mol = 6.02 x 10^23 x 0.87 = 5.24 x 10^23 (2.d.p)
report the elements half life. if we start with 100g of your element (platinum) how long will it take to have 6.26g?
Answer:
did u get the answer yet
Explanation:
which particle diagram represents a sample of oxygen gas at stp
The diagram in image (4) in the image attached represents a sample of oxygen gas at stp.
Oxygen is a diatomic molecule, a diatomic molecule is a molecule that consists of only two atoms of the same element. In this case, the oxygen molecule consists of two oxygen atoms.
If we look at the diagram in the image attached very well, we will discover that the image in diagram (4) shows a molecule composed of two atoms of the same element and this fits exactly into the description of the oxygen molecule.
Learn more about diatomic molecules:
Particle diagram 4 represents the particles of oxygen at standard temperature and pressure.
A model of molecular (or diatomic) oxygen, which is made up of two oxygen atoms attached to each other through a covalent bond.
Dioxygen, also known as oxygen, is a naturally occurring molecule made up of two oxygen atoms that attach to each other with a strong covalent bond to form oxygen (dioxygen). Oxygen is sp3-hybridized, i.e. it has 4 sp3 hybrids. One of these hybrid orbitals overlaps with the s orbitals of hydrogen to create the O-h sigma bonds.
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The diagram in question is attached below.
(iii) Give two reasons why the electrolyte contains cryolite
Answer:
The mixture of cryolite and aluminum oxide has a lower melting point than pure aluminum oxide. This means a lower amount of energy is required to establish effective conditions for electrolysis and thus makes it more cost effective.
Explanation:
in three to five sentences, predict the bonding activity between phosphorus and chlorine. why do you think they would bond that way?
The bonding activity that occurs between phosphorus and chlorine is Covalent Bonding
Covalent bonding is an interaction between two atomic elements that share electrons between themselves.
In Phosphorus Pentachlorine PCl₅, covalent bonding occurs between Phosphorus and Chlorine.
This is because, Phosphorus is the central atom that is attached to 5 different chlorine atoms, each chlorine atom needs one electron each to complete its octet rule and since phosphorus has five valence electrons in its outermost shell, it shares it with each of the chlorine atoms.
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Answer:
Covalent Bonding
what is the oxidation number of oxygen in most compounds
Answer:
2-
Explanation:
Oxygen always act with an oxidation number of 2- unless we're talking of peroxide such as H2O2, where oxygen acts with an oxidation number of 1-
Helppp plzzzz!!!!!!1Asappppp
Answer:
0.178M
Explanation:
The question can immediately be understood as comparing two states.
- The initial state M1 , V1.
- The Final state M2 , V2.
M - Molarity.
V - Volume (in mili liters/ml/ in this case).
The formula is stated as:
M1 * V1 = M2 * V2
Given- Required
M1 = 0.125M V1 = 265ml M2 = ?
V2 = 186ml
Plug these values into the formula above and divide V2 to get M2.rearranged formula - M2 = M1 * V1 / V2 = 0.125M * 265ml / 186ml
= 0.178091397 M ~ ~ 0.178M.
Which two observations are evidence that a chemical change is happening?
A. A yellow liquid forms as a yellow solid is slowly heated.
I B. Bubbles of gas are released when a solid is combined with a
liquid.
I c. Solid crystals form as the temperature of a liquid is lowered.
D. Light and heat are given off after a spark ignites a substance,
Use the chemical equation to complete the activity.
4Fe + 3O2 → 2Fe2O3
Iron (Fe) reacts with oxygen (O2) to form iron oxide. A scientist adds 15.4 grams of Fe to 3.6 grams of O2 to start the reaction. All of the iron and oxygen react to form iron oxide. Explain in detail how you can determine how many grams of iron oxide will be produced.
Use the law of conservation of matter in the explanation.
Answer:
14.54 g Fe2O3
Explanation:
The first step would be to balance the equation but since it's already balanced we don't have to worry about that.
Through the balanced equation, you can find the stoichiometry of the reaction, that is:
4 moles of Fe, react with 3 moles of O2, to produce 2 moles of Fe2O3
Chemistry (accurately stoichiometry) is all about ratios and proportions. The balanced equations gives you the standard ratio by which moles are produced.
So the next step (shown in the paper), is to convert the grams that are giving you in Moles, and you do this by dividing the number of grams given by the molar mass of the substance. The molar mass is the number of grams by which you can find exactly 6.022x10²³ molecules (one mole) of one specific substance.
15.4 g of Fe= 0.28 mol Fe
3.6 g of O2= 0.11 mol O2
Now that you have the quantity of moles, what you need to do is to look for the limitant reactant.
In a balanced equation, the number of moles in the reactants are the rules and they're gonna react completely with each other. If you want x quatity of reactants to react completely, then you will have to respect the proportion to the ratio given in the balanced equation.
But you will rarely follow the proportion so there will usually be a reactant that's gonna be limiting the reaction and one that is in excess. And how do you find this? Well, the easiest way to do it is:
Dividing the number of moles obtained by x element the coefficients of that element in the balanced equation. The one that has the smallest ratio, is the limitant reactants.Since the limitant reactant is gonna be limiting the reaction, all the stoichiometric procedures should be calculated through it, and in this case, the limitant reactant is O2.
But then how to establish the stoichiometric rule to find the number of Iron oxide (III) that's being produced?
Look back to the stoichiometry of the reaction:
To produce 2 moles of Fe2O3, you need 3 moles of O2.
But you have 0.11 mol O2.
Then establish a factor of conversion (shown in the picture)
The result is 0.07 mol of Fe2O3, but you need the answer in grams so you find the molar mass of Fe2O3 and then multiply it by the number of moles (0.07)
The answer is 14.54 g of Fe2O3
CHEMISTRY IS ALL ABOUT PROPORTIONS :D
______= Speed / Wavelength
Answer:
Frequency
Explanation:
It’s kinda self-explanatory but bascially speed=wavelength times frequency
Answer:
Frequency is Speed divided by Wavelength
Step-by-step explanation:
Don't think there needs to be an explanation for the formula, unless you want the conceptual understanding
how much usable energy is extracted from one glucose molecule
We can extract 3×3 power 3 from glucose molecules
7. What is the mass of 389 cm°of propane if the density is 19.3 g/cm?
We are given that–
Volume of Propane is = 389 cm³Density of Propane is = 19.3 g/cm³[tex]\qquad[/tex]________________________
As we know –
[tex]\qquad[/tex][tex] \pink{\bf\longrightarrow {Mass = Volume \times Density } }[/tex]
[tex]\qquad[/tex][tex] \bf\longrightarrow Mass_{(Propane)} = 389 \times 19.3 [/tex]
[tex]\qquad[/tex][tex] \bf\longrightarrow Mass_{(Propane)} = 7507.7 \: g[/tex]
Hence, Mass of Propane is 7507.7 g.[tex]\qquad[/tex]______________________
Mass of a substance is the amount of the constituting particles per unit volume. The mass of the [tex]\bold { 389\ cm^3}[/tex] of propane is 7.507 kg.
Mass of a substance is the amount of the constituting particles per unit volume. It is measured in kilograms (kg).
The formula for mass,
M = v x d
Where,
M - mass
v - volume = [tex]\bold { 389\ cm^3}[/tex]
d - density = 19.3 g/cm
Put the values in the formula,
M = [tex]\bold { 389\ cm^3}[/tex] x 19.3 g/cm
M = 7507.7 g
M = 7.507 kg
Therefore, the mass of the [tex]\bold { 389\ cm^3}[/tex] of propane is 7.507 kg.
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how can knowledge of percent composition help you as a consumer ? how can you promote responsible consumerism ?
Answer:
it is a nice question....my mind tells me that the first is it use me as a good vibes and can use to anything the second i will do my best too absorbe it.
Explanation:
Hope this help...
Mercury is an environmental pollutant that is produced by the burning of
fossil fuels and can be toxic to wildlife and humans. What does this show
about the impact of chemicals on the environment?
A. The harm chemicals could have on the environment outweighs the
benefits that people get from the chemicals.
B. People cannot control the negative effects of chemicals on the
environment.
C. All chemicals that people introduce into the environment are
harmful.
D. The beneficial effects people get from chemicals may have
unintended harmful effects on the environment,
mass of 0.5 moles of co2
Answer:
Mass of 0.5 moles of CO2 is 22 gm.
Explanation:
1 mole of CO2 = 44 gm
0.5 mole of CO2 = 0.5 × 44 = 22 gm
Write the charges for each part of this equation.
Answer:
the Aluminium Al have +3 charges and idion have I) have - 2 charges
Most stars are part of the main sequence of stars in the HR diagram
Question 2 options:
True
False
What role does each type of chemical play in the firework
Answer: Antimony: Antimony is used to create firework glitter effects. Barium: Barium is used to create green colors in fireworks,
Explanation:
Answer:
Explanation:Antimony: Antimony is used to create firework glitter effects. Barium: Barium is used to create green colors in fireworks,
XTRA POINTS 4 CHRISTMAS
What is an empirical formula?
Explanation:
a formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms.
Answer:
The answer is A
Explanation:
its is the chemical formula in which the subscripts are given in the smallest ratio
how does the number of valence electrons change as you move to the right across the periodic table?
Answer:
The number of valence electrons goes up by one each time you move
What causes an echo?
refraction
rarefaction
reflection
please help