Which TWO observations are evidence that a chemical change is happening?
A. A yellow liquid forms as a yellow solid is slowly heated.
B. Bubbles of gas are released when a solid is combined with a liquid.
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.
Answers
Answer: it is B and D light
Explanation: when a spark happens that is changing and bubbles is also changing
Answer:
its B and D
Explanation:
Related Questions
The correct name for p3o2
Answers
The correct name for p3o2 is B. Phosphorus pentoxide.
What is Phosphorus pentoxide?Phosphorus pentoxide (P32O2) is a chemical compound composed of phosphorus and oxygen.
It is a white, crystalline solid that is highly reactive and forms acidic solutions when dissolved in water.
This compound is used in a variety of applications, including as a dehydrating agent, a desiccant, and as a raw material for the production of phosphoric acid and other phosphorus compounds.
In general, Phosphorus pentoxide is a strong oxidizing agent, and it reacts with many organic and inorganic compounds to form new compounds.
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Which are potential sources of error in the experiment? Check all that apply.
estimating temperature to the nearest tenth of a degree
estimating the mass of the sample to the nearest tenth of a gram
estimating the thickness of the foam cups
the position of the cups of sand and water under the heat lamp
the brand of light bulb used for the heat lamp
the air temperature outside the lab
answer A,B,D
Answers
Estimating temperature to the nearest tenth of a degree
Estimating the mass of the sample to the nearest tenth of a gram
The brand of light bulb used for the heat lamp
What is regarded as an error in an experiment?Numerous things can go wrong, including human error, ambient variables, measuring instrument limits, and systematic or random deviations in the experimental technique.
The errors that would occur in this experiment can be seen to stem more from the nature of the estimation and are essentially errors that occur due to the computation of the results.
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The density of water at 4 o C is known to be 1.00 g/mL. Kayla experimentally found the density of water to be 1.075 g/mL. What is the error of Kayla’s measurement? Calculate the percent error.
Answers
Answer:
7.5%
Explanation:
Percent error is this formula: your answer - accepted value divided by accepted value x 100
1.075 g/mL - 1.00 g/mL = 0.075
Divide 0.075 by 1.00 g/mL = 0.075
Multiply 0.075 by 100 = 7.5
The percent of the error in Kayla's density measurement is 7.5%.
The given parameters;
known density of water, ρ = 1 g/mLmeasured density of water, ρ = 1.075 g/mLThe error in Kayla measurement is calculated as follows;
Error = measured value - known value
Error = 1.075 g/ml - 1 g/ml
Error = 0.075 g/ml
The percent of the error in Kayla's density measurement is calculated as;
\(Error \ percent = \frac{Error}{known \ value} \times 100\%\\\\Error \ percent = \frac{0.075}{1} \times 100\%\\\\Error \ percent = = 7.5\%\)
Thus, the percent of the error in Kayla's density measurement is 7.5%.
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a student put a bottle of water and a can of sugared soda in the freezer to chill them quickly . when she took them out , the bottle of water was frozen but the can of soda was not. explain why this happen
Answers
Answer:
it's because the liquid in the bottle is supercooled
Wave A carries more energy than wave B. Wave B must have a smaller than wave A
Answers
Gamma rays have the highest energies, the shortest wavelengths, and the highest frequencies. Radio waves, on the other hand, have the lowest energies, longest wavelengths, and lowest frequencies of any type of EM radiation. Electromagnetic waves cause oscillations in electrical and magnetic fields. It is important to remember that all waves transfer energy but they do not transfer matter . For example, if a ball is placed on the surface of a pond when ripples move across it, the ball will move up and down but not outwards with the wave.
Consider a two step synthetic sequence to generate the chiral cyclopropane. provide the alkyne starting material a, intermediate organic product b, and identify the reagents.
Answers
The formed cyclopropane has cis stereochemistry.
Chiral cyclopropane rings are important pharmacophores in pharmaceutical drugs and bioactive natural products, so libraries of these building blocks are an important resource for drug research and development campaigns.
A synthesis is a set of two or even more reactions that are designed to produce a specific end product. A synthetic step is a single reaction that has to be carried out independently of the other reactions in a synthesis.
The number of steps inside a synthetic sequence equals the number of reactions that need to be performed separately, i.e. the number of reactions that comprise the sequence.
By stereospecific addi-tion of singlet carbenes, cis cyclopropane could be synthesized from cis alkene. Using a Lindlar catalyst, cis alkene could be synthesized from alkynes.
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Which of the following describes an irregular galaxy?
A.) A round football shaped disk
B.) A disk with spiraling arms around it
C.) An oval disk
D.) A random group of stars and no shape
Answers
Answer:
D
Explanation:
They don't have define shape nor structure...so a random group of stars and no shape can form a irregular galaxy
Which of the following gases deviates most from ideal behavior?
A. S02
B. Ne
C. CH4
D. N2
E. H2
Answers
Gases deviate from ideal behaviour when they disobey the KMT of ideal gases, listed above.
In the given choices, SO₂ would deviate from ideal behaviour. Unlike the other options, it is a polar molecule. Polar molecules tend to form stronger intermolecular bonds. As a result, SO₂ gas would not obey the postulate: There are neither attractive nor repulsive forces between gas molecules.
Part of a chemical equation is shown below.
2KOH + H2SO4 → ?
Which pair of chemicals most likely comes after the arrow to complete the equation?
A. 2K + 2H2O
B. 2K2S + SO3
C. K2SO4 + 2HNO3
D. K2SO4 + 2H2O
Answers
Answer: the correct answer is D
Explanation: I just got the quiz finished
The products of the reaction has been potassium sulfate (\(\rm K_2SO_4\)), and water (\(\rm H_2O\)). Thus, option D is correct.
The chemical equation has been the representation of the reactants and the products formed. The reaction of KOH and sulfuric acid has been the neutralization reaction.
The products formed by the neutralization reaction has been salt and water.
The reaction of KOH and sulfuric acid has been:
\(\rm 2\;KOH\;+\;H_2SO_4\;\rightarrow\;K_2SO_4\;+\;2\;H_2O\)
The products of the reaction has been potassium sulfate (\(\rm K_2SO_4\)), and water (\(\rm H_2O\)). Thus, option D is correct.
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Provide any critical observations/changes to the reaction mixture upon addition of the acid. Propose what this might suggest about possible functional groups present on your unknown starting material and briefly defend your proposal. A white precipitate forms with each drop of sulfuric acid.
Answers
This suggests that the unknown starting material is likely an organic compound containing a carboxylic acid functional group.
What is compound ?Compound is a combination of two or more elements which are chemically bonded together. Compounds can exist in both organic and inorganic forms, and are formed when atoms of different elements combine to form molecules. Inorganic compounds are generally composed of metal and non-metal elements, while organic compounds are composed of only carbon and hydrogen atoms. Compounds can also be classified according to their physical state, such as solid, liquid, or gas. Compounds are important in many areas of science, such as chemistry, physics, and biology, and play an essential role in the production of many products, including medicines, plastics, and fuels.
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An object has a mass of 67.4 ounces and a volume of 13.8 cups. What is the density? _______ oz/cup (your answer should *only* be a number, round to one decimal place if needed) *
Answers
Answer:
4.9
Explanation:
Given data:
Mass of object = 67.4 ounce
Volume = 13.8 cup
Density = ?
Solution:
d = m/v
d = 67.4 ounce/13.8 cup
d = 4.9 oz/cup
Thus, density of object is 4.9 oz/cup.
formula for chlorine reacting with lithium and carbon
Answers
Li forms a plus one cation. And Chloride is a minus one anion. But chlorine gas is a homodiatomic molecule.
An industrial synthesis of urea obtains 87.5 kg of urea upon reaction of 68.2 kg of ammonia with excess carbon dioxide. Determine the theoretical yield of urea and percent yield for the reaction.
Answers
Answer:
The theoretical yield of urea = 120.35kg
The percent yield for the reaction = 72.70%
Explanation:
Lets calculate -
The given reaction is -
\(2NH_3(aq)+CO_2\) →\(CH_4N_2O(aq)+H_2O (l)\)
Molar mass of urea \(CH_4N_2O\)= 60g/mole
Moles of \(NH_3\) = \(\frac{62.8kg/mole}{17g/mole}\) (since \(Moles=\frac{mass of substance}{mass of one mole}\))
= 4011.76 moles
Moles of \(CO_2\) = \(\frac{105kg}{44g/mole}\)
= \(\frac{105000g}{44g/mole}\)
= 2386.36 moles
Theoritically , moles of \(NH_3\) required = double the moles of \(CO_2\)
but , \(4011.76<2\times 2386.36\) , the limiting reagent is \(NH_3\)
Theoritical moles of urea obtained = \(\frac{1 mole CH_4N_2O}{2mole NH_3}\times4011.76 mole NH_3\)
= \(2005.88mole CH_4N_2O\)
Mass of 2005.88 mole of \(CH_4N_2O\) =\(2005.88 mole \times\frac{60g CH_4N_2O}{1mole CH_4N_2O}\)
= 120352.8g
\(120352.8g\times \frac{1kg}{1000g}\)
= 120.35kg
Therefore , theroritical yeild of urea = 120.35kg
Now , Percent yeild = \(\frac{87.5kg}{120.35kg}\times100\)
72.70%
Thus , the percent yeild for the reaction is 72.70%
Describe three characteristics of the outer core and explain why the outer core is so important to humans on earth.
Answers
Answer:
The outer core is the only layer that is liquid. It is also mainly made from nickel and iron. The main job of the outer core is that it's responsible for the Earth's magnetic field. As the earth spins, the liquid inside this layer spins aswell, keeping it balanced.
give one example of an element and one example of a compound explain how they are different
Answers
Answer:
Explanation:
Both elements and compounds are classified as pure substances. A pure substance is defined as a material that has a constant composition and fixed properties. Pure substances cannot be separated using physical separation techniques.
Elements are the simplest pure substances. They cannot be broken down or separated by any means, excluding nuclear fission and fusion. Most elements have been found naturally in the universe, most having been formed during the evolution of the universe, in the Big Bang. One example is iron (Fe), formed naturally during the fusion of stars.
Compounds are composed of elements in fixed atomic ratios and can be separated into component elements by chemical means. Examples include Silver bromide (AgBr), which can be separated into silver and bromine by photolytic decomposition (light); sodium chloride can be separated into sodium and chlorine by electrolytic decomposition (electricity); hydrochloric acid can be separated into chlorine upon reaction with water.
Did dalton’s atom have any protons, neutrons, and electrons?
Answers
Answer:
no
Explanation:
No, dalton’s atom haven't any protons, neutrons, and electrons because they were not discovered until later.
Answer:
No
Explanation:
no, because according to him an atom is a tiny indestructible sphere with mass on it. In his theory, Dolton did not know about Protons, neutrons and electrons.
A generator changes______
energy into _____
energy.
Answers
Answer:
mechanical electrical
Explanation:
a generator, in turn, converts the mechanical energy to electrical energy based on the relationship between magnetism and electricity
A container of oxygen with a volume of 60 L is heated from 300 K to 400 k, What is the new volume?
Answers
Answer:
80L
Explanation:
V1/T1 = V2/T2
V2 = V1 T2/T1
T1 = 300K
V1 = 60L
T2 = 400K
V2 = ?
V2 = V1 T2/T1
V2 = (60L)(400K) / (300K)
V2 = 80L
True/False: john added hcl from the buret in 2.00 ml increments and measured the ph after each addition until he reached a ph below 1. this is the proper titration technique.
Answers
False. The described titration technique is not appropriate. It is essential to follow proper titration techniques to ensure accurate results.
The titration technique mentioned, where HCl is added in 2.00 mL increments until the pH drops below 1, is not the correct procedure for a typical titration. In a titration, a solution of known concentration (the titrant) is added incrementally to another solution of unknown concentration (the analyte) until a desired endpoint is reached. The endpoint is often indicated by a color change, formation of a precipitate, or a change in pH.
In acid-base titrations, the pH is monitored to determine the endpoint. The pH will change as the titrant is added, and the goal is to reach a specific pH that corresponds to the stoichiometric equivalence point, where the amount of titrant added is chemically equivalent to the analyte. However, reaching a pH below 1 is not a commonly used indicator for an endpoint in most acid-base titrations.
The proper technique for an acid-base titration involves adding the titrant gradually while monitoring the pH using an appropriate pH indicator or a pH meter. The indicator or meter will show a gradual change in pH until it reaches a point where a sudden and significant change occurs, indicating the endpoint. This method ensures that the titration is conducted accurately and the desired results are obtained.
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The Maxwell-Boltzmann distributions of molecular speeds in samples of two different gases at the same
temperature are shown above. Which gas has the greater molar mass?
(A) Gas A
(B) Gas B
(C) Both gases have the same molar mass.
(D) It cannot be determined unless the pressure of each sample is known.
Answers
Answer: A
Explanation:
I don’t know
Answer:
D
Explanation:
The samples could be at different presssures which would affect the speed/velocity of the particles. Since pressure is a factor, we can't really tell the molar mass of the gases.
What pillar of sustainability is broken by recycling
electronics in India? Should the US make a law that electronics can
only be recycled in the US?
Answers
The pillar of sustainability broken by recycling electronics in India is environmental sustainability. Implementing a law that restricts electronics recycling to the US would not necessarily be the most effective solution, as it overlooks the complex global dynamics of electronic waste management.
Recycling electronics in India often involves improper disposal methods, such as burning or dismantling without proper safety measures. This leads to environmental pollution, including the release of hazardous substances into the air, soil, and water, thus violating the principle of environmental sustainability.
However, simply mandating that electronics can only be recycled in the US may not be the most optimal solution. Electronic waste is a global issue, and restricting recycling to a single country disregards the fact that electronic products are manufactured and consumed worldwide. A more comprehensive approach to addressing electronic waste would involve international cooperation, strict regulations, and monitoring of recycling practices to ensure they meet environmental standards.
Efforts should focus on improving recycling practices globally, including promoting responsible electronic waste management, developing sustainable recycling infrastructure in multiple countries, and encouraging the adoption of safe and environmentally friendly recycling practices. This approach would foster global sustainability and address the challenges associated with electronic waste disposal more effectively than a geographically limited restriction.
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Place following elements in order from largest to smallest atomic radius. S, P, Na, Rb, Cl
Answers
Answer:
Rb>Na>P>S>Cl
Explanation:
In a group from up to down the atomic radius increases
In a row from left to right the atomic radius decreases.
how many grams of h2so4 must be dissolved in 1.08 l of solution to generate a solution with a concentration of 2.69 m
Answers
The mass of H₂SO₄ that must dissolved in 1.08 liters of solution to make 2.69M solution is 271.52 grams.
The molarity of the substance is defined as the number of moles of solute per unit volume of solution in liters.
In this case,
The volume of the solution is 1.08 L.
The required molarity of the substance is 2.69M.
So,
we can write,
Molarity = Moles/Volume
Moles = Molariyt x volume
Moles =2.69 x 1.03
Moles = 2.77
Moles = Mass required/molar mass.
Molar mass of H₂SO₄ is 98 g/mol.
Putting values,
2.77=Mass required/98
Mass required = 271.52 grams.
So, 271.52 grams of H₂SO₄ is required to make 2.69M solution.
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Do the reactants or products contain more energy in the
decomposition reaction of sodium azide?
Answers
Answer:
reactants contain more energy in the decomposition reaction of sodium azide?
Explanation:
The pOH of several solution is given below. Determine pH of each solution and state whether the solution is acidic, basic, or neutral. A) pOH = 2.6 (1pt) B) pOH = 10.5 (1pt)
Answers
Answer:
To determine the pH of each solution and classify them as acidic, basic, or neutral, we need to use the relationship between pH and pOH. The sum of pH and pOH is always equal to 14:
pH + pOH = 14
Let's calculate the pH for each given pOH value:
A) pOH = 2.6
To find the pH, we can subtract the given pOH from 14:
pH = 14 - 2.6
pH ≈ 11.4
Solution A has a pH of approximately 11.4. Since the pH is greater than 7, it is considered basic.
B) pOH = 10.5
Similarly, we can calculate the pH by subtracting the given pOH from 14:
pH = 14 - 10.5
pH ≈ 3.5
Solution B has a pH of approximately 3.5. Since the pH is less than 7, it is considered acidic.
What is the definition of erosion? the process by which sediment settles out of water the soil and rocks deposited by moving water the process by which a river moves soil and rock the waterways that move soil and rock
Answers
Answer:
Sediment moves from one place to another through the process of erosion. Erosion is the removal and transportation of rock or soil. Erosion can move sediment through water, ice, or wind. Water can wash sediment, such as gravel or pebbles, down from a creek, into a river, and eventually to that river's delta.
Explanation:
Erosion refers to the washing away or the removal of top soils/rocks by agents such as water, wind, etc.
What is erosion?Erosion is the removal of topsoils or rocks by agents of erosions. These agents include water, wind, waves, and ice.
In water/ice erosion, topmost soils or rocks are washed away and deposited somewhere else, usually in or at the mouth of nearby water bodies.
Wind erosion carries soils/rocks and deposits them somewhere else. The deposition accumulates over a period of time to form different landforms.
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Given the reaction: HSO4–(aq) + NH3(g) --> NH4+(aq) + SO42–(aq), which statement best describes the action of NH3(g) in the reaction?
Answers
Answer: NH3 (g) would be considered a base because it is a proton acceptor.
Explanation: at the end of the system, NH3 (g) turns into NH4+ (aq) which means it has accepted a hydrogen ion.
According to Bronsted- Lowry concept, bases are proton acceptors. Here, NH₃ is accepting a proton from HSO₄⁻. Hence, NH₃ is a base and option B is correct.
What is Bronsted- Lowry concept of acids and bases ?There are various concepts to define acids and bases. According to Bronsted - Lowry concept, acids are proton donors and bases are proton acceptors.
Acids forms their conjugate base by donating a proton and bases form their conjugate acid by accepting the proton from acid. Here, HSO₄⁻ acts as the acid to donate electron to ammonia.
Hence, NH₃ acts as the base to accept the proton from the acid and forms its conjugate acid NH₄⁺ (ammonium ion). Therefore, option B describes the action of NH₃.
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Your complete question is given below:
in an experiment with 1m ch4, 2m h2s, 1mcs2, and 2mh2, if ch4 is 1.39 m at equilibrium, what are the concentrations of the other substances?
Answers
Generally, Equilibrium is defined as a state in which opposing forces or actions are balanced so that one is not stronger or greater than the other.
Concentration of CH₄ = 1.39
So X here is = -1.39 + 4 = 2.61
So concentration of,
H₂S = 8 - 2 × (2.61) = - 2. 78 M
Cs₂ = 4 - 2.61 = 1.39 M
H₂ = 8 - 4 (2.61) = -2.44 M
Concentration is defined as the amount of a substance, such as a salt, that is in a certain amount of tissue or liquid, such as blood. When less water is present in a substance it usually becomes more concentrated.
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Which of the following would not be part of a study plan to learn chemistry?
A) study a little everyday
B) skip your instructors study hours
C) form a study group
D) read the chapter before class
E) work the sample problems
Answers
The following that would not be part of a study plan to learn chemistry is (B) Skip your instructor's study hours.
All of the other options are good study habits that can help you learn chemistry. Studying a little bit every day helps you retain the information better. Forming a study group can help you learn from each other and stay motivated. Reading the chapter before class gives you a foundation to build on during lecture. And working the sample problems helps you practice what you've learned.
However, skipping your instructor's study hours is not a good idea. Your instructor is there to help you learn the material, and they can give you personalized feedback on your work. If you're struggling with the material, skipping their study hours will only make it harder for you to succeed.
So, if you're serious about learning chemistry, make sure to include all of the good study habits in your plan, and skip the bad ones.
Here are some additional tips for creating a study plan to learn chemistry:
Set realistic goals for yourself. Don't try to learn everything in one day.Find a quiet place to study where you won't be interrupted.Take breaks when you need them.Reward yourself for your hard work.Therefore, (B) Skip your instructor's study hours is the correct answer.
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Why does the equilibrium of a system shift when the pressure is decreased?
To maximize the stress on the system
To stop restoring equilibrium to the system
To increase the total moles of gas in the system
To decrease the total moles of gas in the system
Answers
When the equilibrium of a system shift to increase the total moles of gas in the system, when the pressure is decreased.
What is equilibrium law?Equilibrium law states that when any external stress is applied on the equilibrium state of the reaction then reaction will shift towards that side where external stress decreases.
Relation between pressure and moles of gas is directly proportional to each other. So when pressure is decreased then to maintain the equilibrium total moles of the gas of the system will increases as a result of which pressure increases.
Hence, equilibrium shift to increase the total moles of gas in the system.
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Answer: to maximize the stress on the system
Explanation: i took the test