EASY QUESTION IS SCIENCE PLEASE HELP.
A student says that all pure substances are elements. Do you agree? Why or why not?
A student says that all pure substances are elements. Do you agree? Why or why not?
I agree. Pure substances include only single atoms made of one element.
I disagree. Elements are not pure substances. All pure substances include only molecules and compounds, which are more complex.
I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds.
I disagree. All pure substances are also mixtures.
A student says that all pure substances are elements. Do you agree? Why or why not?
i don't. pure substances include elements, compounds and crystals. they would've been correct if they stated all elements were pure substances.
or
I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds.
what is the theoretical yield of bromobenzene in this reaction when 30.0g of benzene reacts with 65.0 g of bromine?
The theoretical yield of bromobenzene in this reaction when 30.0g of benzene reacts with 65.0 g of bromine is: 46.153 %
To solve this problem the theoretical yield formula and the procedure we will use is:
theoretical yield = relation between reactants * 100
Information about the problem:
m(benzene) = 30.0gm(bromine) = 65.0 gtheoretical yield=?Applying the theoretical yield formula we get:
theoretical yield = (30.0g * 1g /65.0 g) * 100
theoretical yield = 46.153 %
What is the yield of a reaction?In chemistry, the yield of a reaction is the amount of product obtained from the conversion of the reactants in a chemical reaction.
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A fall outbreak of influenza caused many absences at work and school. Health department
officials sent out warnings to use precautions when coughing and to wash hands
thoroughly. Which members of the population are a primary concern?
Influenza viruses spread mainly through droplets of respiratory secretions in the air, typically generated by coughing and sneezing.
What is Influenza viruses?A contagious illness brought on by influenza viruses, influenza is also referred to as "the flu." Flu-like symptoms, which can range in severity from moderate to severe, frequently include fever, runny nose, sore throat, muscle discomfort, headache, coughing, and exhaustion. After being exposed to the virus, these symptoms usually appear one to four days later and remain for two to eight days.
Especially with children, diarrhea and vomiting can happen. Pneumonia, which can be brought on by the influenza virus or a subsequent bacterial infection, may develop from the viral-related illness. Other side effects of infection include meningitis, encephalitis, acute respiratory distress syndrome, and deterioration of pre-existing conditions like asthma and cardiovascular disease.
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What's the balanced equation of 3Fe + 4H2O→Fe3O4 + 4H2?
The balanced equation of Fe + [tex]H_{2} O[/tex] → [tex]Fe_{3} O_{4}[/tex] + [tex]H_{2}[/tex] is given as ,
3 Fe + 4[tex]H_{2} O[/tex] → [tex]Fe_{3} O_{4}[/tex] + 4[tex]H_{2}[/tex]
The balance equation is the equation in which number of atom in reactant side is equal to number of atom in product side .
The inclusion of stoichiometric coefficients to the reactants and products is necessary to balance chemical equations . This is significant because a chemical equation must adhere to the laws of conservation of mass and constant proportions , meaning that both the reactant and product sides of the equation must include the same amount of atoms of each element .
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H2(g) + Br2(g) → 2HBr(g)
The above reaction is carried out at 25oC. ΔH is -72 kJ mol-1 and ΔS is - 106 J mol-1K-1, the reaction will
A. not proceed spontaneously at the given
B. proceed spontaneously at the given temperature
C. proceed in the reverse direction at the given temperature
D. proceed spontenously at lower temperature
Given the conditions for a reaction to be spontaneous under a given set of reaction conditions, the reaction not proceed spontaneously at the given temperature; option A
What are spontaneous reactions?Spontaneous reactions are reactions that proceed without an input of extra energy as the reaction favors the formation of products under the given reaction conditions.
For spontaneous reactions, free energy change, ΔG is negative and entropy ΔS is positive.
Given the above reaction occurring at the given conditions:
H₂ (g) + Br₂ (g) → 2 HBr(g)
The reaction was carried out at 25 °C.
ΔH is -72 kJmol⁻¹ and ΔS = - 106 Jmol⁻¹K⁻¹
The reaction is an exothermic reaction at room temperature
The entropy, ΔS of the reaction is negative indicating that the reaction is not spontaneous at that temperature.
Therefore, correct conclusion will be that the reaction is exothermic at the given temperature but will not proceed spontaneously under the given conditions.
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How many valence electrons makes an atom chemically unreactive? (1 pt)
*
1 point
1
7
8
11
8
Explanation:The octet rule explains reactivity in relation to valence electrons.
Valence Electrons
Firstly, let's define valence electrons. Across the periodic table, elements can have a wide range of total electrons. However, when discussing reactions, valence electrons are the most important. Electrons arrange themselves according to energy levels. Any electrons that are on the outermost energy level are considered valence electrons. Most valence energy levels, also called valence shells, hold 8 electrons.
Octet Rule
Now that we know what valence electrons are we can use them to determine reactivity. It is important to note that atoms are most stable when their valence shell is full (as supported by Hund's rule). The octet rule explains atoms will always attempt to fill their valence shell in order to become stable. If an atom has only a few valence electrons, then it will attempt to lose its electrons. On the other hand, atoms that almost have a full valence shell will attempt to gain new electrons.
The losing or gaining of electrons occurs during reactions. So, if an atom already has 8 valence electrons then it will not react. It is already stable, so it has no need to lose or gain more electrons.
Exceptions
While the octet rule explains a lot, like all rules in chemistry it has exceptions. The most common exceptions are hydrogen and helium. Due to the size of these atoms their valence shell can only hold 2 electrons. So, these atoms are actually unreactive at 2 valence electrons.
Another exception can be seen with sulfur and xenon. Both of these atoms are hypervalent. This means they can react even if they have 8 valence electrons. However, this exception is less common.
Do the follow reactions depict heat of formation reactions? if so, mark the reaction as yes, if it is not a heat of formation reaction, then choose no.
The amount of heat created or absorbed during a reaction that takes place under a constant amount of pressure is measured by the enthalpy change.
What causes formation heat to be produced?The change in enthalpy that occurs as one mole of a compound is created from its component parts is known as the "heat of formation." The total amount of energy that should be added to or released during a chemical reaction is known as the heat of reaction.
What signs do you see when heat is produced?By deducting the total of the standard enthalpies of formation of the reactants from the sum of the standard enthalpies of formation of the reactants and products, one can determine the standard enthalpy change of formation.
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When Using a gas tube spectroscopy , how does it give off a certain color or colors? Explain in terms of electrons. What scientist discovered this?
When Using a gas tube spectroscopy , it give off a certain color or colors when Electrons which are in the gaseous atoms first starts to get excited, and then they tend to fall back to smaller form of energy levels, thereby emitting light that is of a unique color in the process.
What scientist discovered this?Isaac Newton through his experiment in 1666.
Why does a gas discharge tube have a certain color?Energy often excited if the electrons in the gases tends to move to a higher energy states.
Note that for them to be able to get back to the ground state, electrons need to let off excess energy and this is often done in the form of light. The light is said to have different color in all of the tube because of they have different wavelengths of light that need to be released.
Therefore, When Using a gas tube spectroscopy , it give off a certain color or colors when Electrons which are in the gaseous atoms first starts to get excited, and then they tend to fall back to smaller form of energy levels, thereby emitting light that is of a unique color in the process.
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Describe how atoms form positive ions by losing electrons or negative ions by gaining electrons
Atoms form positive ions by losing electrons or negative ions by gaining electrons through a special type of chemical combination called electrovalent or ionic combination.
How atoms of sodium and chlorine combine together to form their ionsIt follows that metals are electropositive elements which donates its valence electrons to the nonmetals. The atoms which donates its electrons become positively charged while the species that recieve electrons become negatively charged.
In the formation of sodium chloride, sodium donates its 1 valence electron to chlorine become positively charged; Na+ and chlorine which recieves the electron to add to it's 7 valence electrons become negatively charged; Cl-
Na + Cl ---- Na+Cl-
So therefore, atoms form positive ions by losing electrons or negative ions by gaining electrons through a special type of chemical combination called electrovalent or ionic combination.
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John has a solution. It turns yellow when he adds red cabbage juice. Predict what colour the solution would turn if he added hibiscus- flower juice. Explain your answer.
As the solution turns yellow when re cabbage juice indicator is added it implies that its base solution so the color of the solution when hibiscus flower juice added is dark grey to green.
when hibiscus indicator added Anywhere from dark pink to pale pink usually indicates an acid, while dark gray to green colors usually indicate a base.
Dark blue should be the color of red cabbage indicator. The cabbage indicator's color will shift to red or pink if the solution is an acid, and to green or yellow if the solution is a base. In the event that the test solution is neutral, it will stay purple or blue
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a typical atom has a diameter of about 1.0 × 10-10 m. approximately, how many atoms are there along a 1.0-inch line?
The number of atoms in 1 inch is 240 billion atoms
Given:
diameter of atom = 1.0 × 10^-10 m
To Find:
atoms are there along a 1.0-inch line
Solution:
1 inch = 0.254 m
0.254 m = 1 inch
1 m = 1/0.254 = 3.93 inch
1.0 × 10^ -10 = 3.93 x 1.0 × 10^-10 = 3.93 x 10^-10 inch
3.937 x 10-2 inches. This is approximately 4 one-billionths of an inch.
Divide 24 cm by the atomic diameter to get the number of atoms.
24/ (1.0 x 10^-10)= 24 x 10^10 = 2.4 x 10¹¹
240 billion atoms
Hence, the number of atoms in 1 inch is 240 billion atoms
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6. CCC Patterns Compare the ions of elements listed in the table with the atoms of the element. For example, compare the fluorine ion to the fluorine atom. Based on the similarities and differences between the two, write a definition for "ion.'
The number of protons and electrons in an atom is equal, making them neutral particles. According to definition, an ion is an electrically charged particle that is created by either taking electrons from a neutral atom to generate a positive ion or adding electrons to produce a negative ion.
Take note that while the ion is known as fluoride, the atom is called fluorine. The electronic structure of a fluoride ion is similar to that of a neon atom (Ne). A fluoride ion, however, is not a neon atom. A fluoride ion's nucleus, which is an atom of fluorine, has 9 protons, but the nucleus of a neon atom has 10.
The fluorine atom has nine electrons, but the fluorine ion (flouride) has ten, meaning that while fluorine has nine protons and electrons, the flouride has one more electron than the fluorine atom does, which has nine and ten electrons respectively.
While flouride is negatively charged electrically, fluorine is electrically neutral.
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Help with number 2
2. Which of the following does not describe a pure substance?
(A)
B
D
Molecules of the same type of atom attracted to each other
Molecules of different types of atoms that are not attracted each
other
Individual atoms of different types repeated to form extended
structures
Individual atoms of the same type connected to form extended
structures
Answer:
B
Explanation:
This is because due to the fact that they are not attracted to each other they do not form a solution
explain any industry that uses heavy chemical as raw materials production
Answer: This may help you
https://ay.live/1vVB3
Explanation:
Which list includes only physical properties?
Element X has a half life of 6 days. If you start with 50 kg of element
how much would be left after 3 days?
12.5 kg
25 kg
50 kg
35.35 kg
12.5 grams will be left.
Given:
half life of X= 6 days
Initial amount - 50 kg
Amount left after 3 days = ?
Half life - The period of time needed for anything to go through a process in which half of it participates, for example, the period of time needed for half of a radioactive substance's atoms to disintegrate. It means after half life the element will become half its quantity.
A quantity's half-life (symbol - t1/2) is the amount of time needed for it to decrease to half of its initial value. In nuclear physics, the phrase is frequently used to indicate how rapidly unstable atoms decay radioactively or how long stable atoms last.
According to the question, If half life is 6 days and we start with 50 kg of element, after 6 days it will become 25 kg and after 3 days it will become 12.5 grams .
t¹/₂ = 6 days
Initial amount = 50 kg
After half life = 50/2
= 25 kg
∴ After 3 days = 25/ 2
= 12.5 kg
Hence, 12.5 kg is left after 3 days.
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True or false? Dimensional analysis is the study of space and time. Why?
Answer:
False.
Explanation:
Dimensional analysis is a way of converting quantities. The study of space and time is cosmology.
What is the density of a liquid with a mass of 31.1415 g and a volume of 30.13 ml?
The liquid with a mass of 31.1415 g and a volume of 30.13 ml has a density of: 1.033 g/ml
The density formula and the procedure we will use is:
d = m/v
Where:
v= volumed= densitym= massInformation about the problem:
m = 31.1415 gv =30.13 mld= ?Applying the density formula we get:
d = m/v
d = 31.1415 g/30.13 ml
d = 1.033 g/ml
What is density?It is a physical quantity that expresses the ratio of the body mass to the volume it occupies.
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which observation most likely indicates that only a chemical change has taken place?(1 point) states of matter changes. states of matter changes. the change cannot be reversed. the change cannot be reversed. a reaction occurs. a reaction occurs. the shape changes. the shape changes.
The correct answer as to which observation most likely indicates that only a chemical change has taken place would that the change cannot be reversed.
What is a Chemical change ?A chemical change is the transformation of one substance into another, the emergence of new compounds with distinct properties, or any combination of these. It happens when two compounds mix to create a new material (synthesis or either decomposes to form more substances)
Burning, frying, rusting, and rotting are a few instances of chemical transformations. Boiling, melting, freezing, and shredding are a few examples of physical changes.When bonds between molecules or atoms are created, disrupted, or both, chemical changes result. This implies that a material is changed from one with a certain set of attributes (such as melting point, colour, flavour, etc.) into another with a different set of properties.Learn more about Chemical change here:
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Convert 5.70 kilograms to milligrams show your work
5.70 kg = 5700000mg
kg- The International System of Units (SI) uses the kilogram (sometimes known as the kilogram) as the unit of mass.
mg- a unit of mass or weight that weighs 0.0154 grains or one thousandth of a gram.
Conversion is important because It's necessary to convert units; it's not merely important. Scientists and engineers have miscommunicated, leading to the loss of space probes.
You are aware that 1,000 g make up 1 kilogram.
After that, change 1 kilogram to milligrams.
To convert from grams to milligrams, multiply the number of grams by 1,000.
A kilogram is equivalent to one million milligrams.
∵1 Kg = 1000000 mg
∴ 5.70 kg = 5.70 x 1000000
= 5700000 mg
Hence , 5.70 kilograms equals 5700000 milligrams.
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using a electron miscroscope, jane measured a rod-shaped bacterium and found it to be 0.00099345 meters in lenght. list the steps she should take to represnt this number
The transmission electron microscope (TEM) works much like a light microscope, transmitting a beam of electrons through a thin specimen and then focusing the.
What is transmission electron microscope?A stream of electrons is sent through a specimen during transmission electron microscopy (TEM), which produces a picture of the sample. The specimen is often a grid- or suspension-supported ultrathin segment that is less than 100 nm thick. As the beam passes through the specimen, a picture is created due to the interaction of the electrons with the material. The picture is subsequently enlarged and focussed onto an imaging device, such as a fluorescent screen, a sheet of photographic film, or a sensor like a scintillator linked to a charge-coupled device.
Due to the electrons' shorter de Broglie wavelength, transmission electron microscopes can image at a resolution that is substantially higher than that of light microscopes.
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question: Using an electron microscope, Jane measured a rod-shaped bacterium and found it to be 0.00000345 meters in length. List the steps she should take to represent this number in scientific notation.
Answer:
The coefficient of this value in scientific notation is 3.45.
The decimal point needs to be moved six places to the right, so the exponent is -6.
0.00000345 = 3.45 × 10-6
Explanation: edmentum sample answer
is mgco3 + 2hcl > mgcl2 + H2O + CO2 a redox reaction
Create a chart that compares physical and chemical properties. Give two examples for each type of property
Answer:
look the image
Explanation:
Copper ions, cu+2, are produced in solution during bioleaching. write an ionic equation for the displacement reaction between these copper ions and iron. include state symbols
An ionic equation for the displacement reaction between copper ions and iron: Cu²⁺(aq) + Fe(s) → Cu(s) + Fe²⁺(aq)
In this chemical reaction, there is a transfer of electrons from iron (Fe) to copper (Cu).
Iron change oxidation number from 0 to +2 (loose electrons) and copper change oxidation number from +2 to 0 (gain electrons).
Oxidation half reaction: Fe⁰ → Fe²⁺ + 2e⁻.
Reduction half reaction: Cu²⁺ + 2e⁻ → Cu⁰.
Oxidation is increase of oxidation number.
Reduction is lowering oxidation number because atom gain electrons.
(aq) is an aqueous solution.
(s) is a solid, insoluble in the water.
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equilibrium and dynamical characteristics of hydrogen bond bifurcations in water–water and water–ammonia dimers: a path integral molecular dynamics study
The path integral molecular dynamics study describes the effects of nuclear quantum fluctuations on the dynamical and equilibrium characteristics of bifurcation pathways in hydrogen-bonded dimers combining ammonia and water.
At the order of 20 K of cryogenic temperatures , the hydrogen atoms in the molecules along these isomerizations acting as hydrogen-bond donors interchange their original connective characters. It comprises three stages in the resulting quantum transition paths, the final and the initial states comprise general rotations during which two protons possess their classical-like characteristics
The impacts from quantum fluctuation are displayed in the changes operated at the medium passages over transition states, as the proton's spatial extents stretch over usual lengths comparable to the distances between dangling and connective basins of attractions.
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Is this statement true or false?
There is nothing we can do to help prevent soil erosion. Only scientists and farmers can work on solutions.
Answer: F
Explanation:
we can prevent soil erosion by reducing the amount of water and blockages that might build water up and erode the soil around farmland/other
complete the mechanism for the base‑catalyzed racemization of the chiral ketone by adding any missing atoms, bonds (including wedge and dash bonds), charges, nonbonding electrons, and curved arrows (forward reaction only). step 1: draw curved arrows.
The chiral ketone (2R) -2-methyl-1-phenylbutan-1-one is converted into
(2S)-2-methyl-1-phenylbutan-1-one by base‑catalyzed racemization.
The mechanism of base‑catalyzed racemization of the chiral ketone is as above.
What is Ketone?Ketone is defined as the organic compounds having C=O as a functional group.
What is Chiral Ketone?Chiral ketone are those in which the the alkyl group bonded with C=O are same.
What is base‑catalyzed racemization?Base‑catalyzed racemization is defined as a process in which the optically active compounds which is consist of only one enantiomer are allow to converted into an equal mixture of enantiomers having zero optical activity in the presence of catalyst which is basic in nature.
Racemization rates are mainly dependents on the molecule and conditions some of them are pH and temperature.
Thus, we concluded that the chiral ketone (2R) -2-methyl-1-phenylbutan-1-one is converted into
(2S)-2-methyl-1-phenylbutan-1-one by base‑catalyzed racemization.
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the density of water at 4 degree celsius is 1.00 g/ml britanny takes a sample of water and finds the mass to be 16.7 g and the volume to be 16.2 what was her percent error
The mass is 16.7 g and the volume is 16.2. The percent error is 2 percent.
What is the percent error?Percent error is the difference between the estimated value and the calculated value. Percent error is calculated by the actual value subtracted by the expected values divided by the expected value.
Given, that the density is 1.00 g/ml
The temperature is 4-degree celsius
The mass is 16.7 g
The volume is 16.2 l
Density = m/v 16.7 / 16.2 = 1.03 which is the actual value
The estimated value is 1.00 g/ml
The formula is
1.03 - 1.00 / 1.00 = 0.02
0.02 x 100 = 2 %
Thus, the percent error is 2 %.
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the property of water molecules that is responsible for all the other physical and chemical properties is
The hydrogen bonding of water is one of the main property of water which makes it responsible for all the other physical and chemical properties.
Water molecules are polar in nature and they form hydrogen bonds. Hence, they have a high boiling point , high specific heat and density. Water can exhibit the properties of an acid, as well as a base (amphoteric character). The water molecules are constantly moving and the hydrogen bonds continuously breaks and forms again. These hydrogen bonds are strong, which is the reason for the unique properties of water.
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True or False?
Electricity is a benefit from science that we use.
Answer: This is True
Explanation: I'm only writing this part so that it counts. :)
Answer: True
Explanation: because you got to understand we use electricity every day.