Which describes the enthalpy change associated with an endothermic reaction? *
2 points
ΔH is negative
ΔH is zero
ΔH is positive
Answer:
It is negative because the enthalpy of the products is greater than the enthalpy of the reactants.
1. Which would dissolve faster?
A. individual salt crystals
B. a big block of salt
2. most cases , when temperature increases , solubility
A. increases
B. decreases
3. As agitation increases , the rate at which a solute will dissolve
A. increases
B. decreases
1) A. individual salt crystals
2) A. increases
3) A. increases
hope this helps :)
A solution is defined as the homogeneous mixture which contain one or more solutes in a solvent. The factors which affect the solubility are temperature and pressure. Here individual salt crystals dissolve faster.
What is solubility?The maximum amount of solute which can dissolve in a given quantity of the solvent at a certain temperature is defined as the solubility. It is defined as the property exhibited by a material to dissolve in a given solvent.
The powdered salt found to dissolves faster in a solvent than the salt of larger size. The rate of dissolving is affected by the size of the solute. The faster the solute dissolves if its size is smaller. So the individual salt crystals dissolves faster.
In most cases, generally the solubility found to decrease with the increase of temperature. When the temperature increases, the kinetic energy of the molecules increases and thereby decreases the intermolecular force of attraction. The increase in the process of agitation decreases the solubility.
1. The correct option is A
2. The correct option is B
3. The correct option is B
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what is the molarity of a solution in which 65.3 NaNO3, are disssolved in enough water to make 1250 mL of solution?
Answer:
1242
Explanation:
Algae are microscopic plants that grow in the ocean. Algae must have sunlight, nutrients, and water to survive. They conditions are called _______
for algae.
The condition is called phytoplankton because algae are microscopic, need sunlight and nutrient, water to survive.
What is phytoplankton?Phytoplankton refers to microscopic marine algae and they are also called microalgae.They are similar to terrestrial plants in that they contain chlorophyll and require sunlight in order to live and grow. Most phytoplankton are very buoyant and float in the upper part of the ocean, where sunlight enter the water and they get the sunlight to produce food.
Algae photosynthesized,that is they use sunlight in the presence of chlorophyii and carbondioxide to produce food and oxygen.
Therefore, The condition is called phytoplankton because algae are microscopic, need sunlight and nutrient, water to survive.
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b
Identify a compound composed of
molecules
Answer:
nitrogen oxides and hydrogen
Daffodils and tulips are examples of which of these?
a.cuttings
b.bulbs
c.runners
d.tubers
Answer: bulbs
Explanation: Daffodils and tulips are examples of bulbs.
Answer: Bulbs
Explanation: When you plant daffodils or tulips, you will see that the "seeds" are onion-like. Onions are bulbs, and so are daffodils and tulips.
A) 2 and 3 only
B) 1 and 4 only
C) 2,3,4 only
D) all of the above
choose one correct answer
Answer:
D
[tex] \: \: \: \: [/tex]
What happens to a catalyst as the result of a chemical reaction?
A.) It slows a chemical reaction.
B.) It is not consumed.
C.) It is consumed.
D.) It changes to something else.
The catalyst is recovered unchanged in amount and chemical composition at the end of a reaction. It speeds up only a spontaneous reaction, not a spontaneous one. It is not consumed in a reaction. The correct option is B.
What is a catalyst?A substance which increases the rate of a reaction without itself undergoing any permanent change chemically or quantitatively is defined as the catalyst and the phenomenon is known as the catalysis. It is believed that a catalyst actually participates in the chemical reaction that it speeds up.
A catalyst does not affect the position of equilibrium of a reversible reaction and thus do not alter its equilibrium constant. This is because it speeds up the forward and backward reactions to the same extent. It shows some specificity in its action.
It does not alter the Gibbs energy.
Thus the correct option is B.
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Would the ph at the equivalence point be acidic, basic, or neutral for each given titration?.
The pH at equivalence point depends on the nature of the acid-base titration, and can either be acidic, basic, or neutral.
What is equivalence point?The equivalence point in a titration is the point at which equal amount of acid and base have reacted with each other.
The pH at equivalence point depends on the nature of the acids and bases being titrated.
pH at equivalence point will be:
neutral in a strong acid and strong base titrationacidic in a strong acid and weak base titration basic in a weak acid and strong base titrationTherefore, the pH at equivalence point depends on the nature of the acid-base titration.
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_______ oxides are oxides of certain non metals
acidic in naturenature
Generally, Oxides of non-metals are acidic in nature. When non-metals are reacted with water it forms an acidic solution. The common oxides of Sulphur, Selenium, and Bromine are strongly acidic.
Marble(calcium carbonate) reacts with hydrochloric acid(hcl) to form calcium chloride solution, water, and carbon dioxide. Find the percent yield of carbon dioxide if 3. 65 grams
Answer:
When calcium carbonate reacts with hydrogen chloride, it reacts to form calcium chloride, carbon dioxide, and water. If this reaction occurs with 51.6% yield, what mass of carbon dioxide will be collected if 16.93 g of CaCO3 is added to sufficient hydrogen chloride
On the basis of the information below, the dissolution of FeF2(s) in acidic solution is A. thermodynamically favorable, because K2 > 1 B. thermodynamically favorable, because K3 > 1 C. not thermodynamically favorable, because K1<1 D. not thermodynamically favorable, because K3 < 1 hint (Hess's law) FeF2(s) – Fe2+(aq) + 2 F"(aq) F"(aq) + H+ (aq) 2 HF(aq) FeF2(s) + 2 H+ (aq) 2 Fe2+ (aq) + 2 HF(aq) K1 = 2 x 10-6 K2 = 1 * 103 K3 = ?
Since K3 is greater than 1, the reaction is thermodynamically favorable.
Data;
FeF2 is in an acidic solutionK2 > 1 is thermodynamically favorablek3 > 1 is not thermodynamically favorableK1<1 is not thermodynamically favorableHess LawThis states that the heat change in a given chemical reaction is the same irrespective of the number of process in which the reaction is effected.
Using Hess Law;
[tex]rxn_3 = rxn_1 * 2rxn_2\\k_3 = k_1 * k_2^2\\k_3 = 2*10^-^6 * (1*10^3)^2\\k_3 = 2[/tex]
substituting this using Gibbs law,
[tex]\delta G^0_3 = -RT\ln K_3\\\delta G^0_3 < 0[/tex]
Since K3 is greater than 1, the reaction is thermodynamically favorable.
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Which of the following pH values indicates the most basic solution? A. 3 B. 7 C. 8 D. 11
formation of a solid, formation of a gas, and a color change can also occur during some physical changes. give examples of physical changes that could produce these clues. what evidence suggests that the changes you observed in test tubes 1-3 were, in fact, chemical changes
Answer:
Examples of these physical changes are melting ice-cream, or boiling water as well as freezing it. Adding dye to water is also a physical change since the chemical compounds remain the same, it is only the physical appearance that changes.
Possible reasons for chemical changes are the formation of a precipitate (solid), or formation of gas (bubbling) as well as release of heat or light or release of odor.
A reaction that is spontaneous at low temperature can become non spontaneous at high temperature if δh is\
Answer:
Reaction
Explanation:
A reaction that is spontaneous at low temperature
Predict which one of the following salts is used for softening water?
A) [tex] Na_{2} SO_{4}[/tex]
B) [tex] Na_{2} Si O_{3}[/tex]
C) [tex] Na_{2} CO_{3}[/tex] x [tex] 10 H_{2}O[/tex]
D) [tex] NaClO_{3} [/tex]
Salts such as [tex] Na_{2} SO_{4}[/tex] are used in softening of hard water.
What is hardness of water?Hardness of water is the presence on water of dissolved metallic ions such as calcium and magnesium ions results in the water having additional properties such as taste.
Hardness of water is of significance in the laundry industry as it causes water to lather with difficulty and also produces sc_um.
To remove hardness of water or to soften water, salts such as [tex] Na_{2} SO_{4}[/tex] are used.
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Write a full note on Infectious diseases. please I need it now and no links please thanks
Answer:
diseases where microbes are the immediate cause are called infectious diseases. Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites. Many organisms live in and on our bodies. They're normally harmless or even helpful.
Two substances are combined and react. After 10 minutes, the chemical reaction has reached equilibrium. Which values would be equal to zero for the solution?
The extra conversion of concentration of reactant and product should be zero in order to attaining equlibrium state.
What is equilibrium?Chemical equilibrium refers to the state in which both the reactants and products are present in equal concentrations or amount. In equlibrium, same amount of reactant is converted into product and product into reactant.
So we can conclude that the extra conversion of concentration of reactant and product should be zero in order to attaining equlibrium state.
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Complete and balance the following half-reaction in acidic solution mno4 ---> mno2
The completely balanced reaction of the half-reaction in acidic solution is ; MnO₄⁻ (aq) + 3e⁻ + 4H⁺ ------> MnO₂(s) + 2H₂O(l)
Given data :
The half-reaction in acidic solution
MnO₄⁻ (aq) --> MnO₂(s)
Complete and balance the Half-reactionDetermine the oxidation number on both sides
Oxidation number of Mn in MnO₄⁻ = +7
Oxidation number of Mn in MnO₂ = +4
First step : Balance the oxidation number
MnO₄⁻ (aq) + 3e⁻ ------ > MnO₂(s)
Next step : Balance the charge in the reaction
MnO₄⁻ (aq) + 3e⁻ + 4H⁺ ------> MnO₂(s)
Final step : Completely balance the half reaction
MnO₄⁻ (aq) + 3e⁻ + 4H⁺ ------> MnO₂(s) + 2H₂O(l)
Hence we can conclude that The completely balanced reaction is :
MnO₄⁻ (aq) + 3e⁻ + 4H⁺ ------> MnO₂(s) + 2H₂O(l)
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N2(g)+3H2(g) 2NH3(g)
The equilibrium system described by this equation has
reactant molecule(s)
and
product gas molecule(s).
Considering the definition of chemical equation, the equilibrium system described by this equation has 4 reactant molecules and 2 product gas molecules.
Definition of chemical equationA chemical equation is a symbolic description used to describe the identities and relative quantities of the reactants and products involved in a chemical reaction.
The information contained in the chemical equation allows us to determine the substances that are transformed or modified in a reaction, called reactants or reagents, and the new substances that originate in a chemical reaction, called products.
The chemical equation must comply with the Law of conservation of matter. That is, the equation must indicate that the number of atoms of the reactants and products is equal on both sides of the reaction and that the charges are also equal.
Number of reactant molecule(s) and product gas molecule(s)In this case you know:
N₂ + 3 H₂ ⇄ 2 NH₃
You can observe that the number of H₂ is 3, while the number of N₂ is 1.
The number of molecules on the reactant side is the sum of hydrogen and nitrogen molecules. Then, the total number of reactant molecule is 4.
The number of product molecules are only the number of NH₃. Then, the number of product molecules are 2.
Finally, the equilibrium system described by this equation has 4 reactant molecules and 2 product gas molecules.
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Answer:
4 and then 2
Explanation:
12. You want to create a 0. 55M Potassium Chloride solution. You mass 3. 00 grams of Potassium chloride
How much water is needed?
I suppose that you want to produce a 0.25 M solution of KCl
You do not want tp produce 0.25 mol of KCl.
Molar mass KCl = 39.1 + 35.45 = 74.55 g/mol
Mass of 0.25 mol KCl = 0.25 mol * 74.55 g/mol =18.64 g
To produce a 0.25 M solution of KCl = 18.64 g would require a solution volume of 1.0 L or 1000 mL
You have only 5.00 g ( NOT 5.00 gm) of KCl
Volume of solution required = 5 g / 18.64 g * 1000 mL = 268 mL solution
You dissolve the 5 g KCl in some water and then make up the final solution volume to 268 mL
This does NOT mean that you dissolve the 5 g KCl in 268 mL water .
A chemist adds 36.0 g of sodium chloride to 200 g of water at STP and all of the sodium chloride dissolves. What is the solute in this scenario?
A. Sodium
B. Sodium Chloride
C. Water
The solute in the scenario where a chemist adds 36.0 g of sodium chloride to 200 g of water at STP and all of the sodium chloride is sodium chloride.
What is a solute?A solute is a substance that forms a solution with another substance called solvent in a process called solubility.
According to this question, a chemist adds 36.0 g of sodium chloride to 200 g of water at STP and all of the sodium chloride dissolves in the water.
This shows that the sodium chloride is the solute added to the water (solvent).
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This part insulates the reaction chamber from the transfer of heat to or from the surrounding environment. this part contains a known amount of water, which is placed there before the experiment starts. this part is where the metal is placed at the beginning of the experiment. this part is used for measuring the initial and final temperatures of the water.
The amount of heat transferred in and out of the system is measured by calorimetry. The thermometer in the calorimeter is used to measure the temperature.
What are the parts of the calorimetry device?The thermometer (A) is a device used to measure the final and the initial temperature of the water or any other liquid in a system. A metal vessel is a place where the reaction mixture is present.
In-vessel (B), water, and metal are placed before the beginning of the experiment. The styrofoam cup or the outer metal vessel (C) insulates the instrument, from regulating the heat transformation.
Therefore, part A measures the temperature of the reaction mixture.
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Definition of Tissue:
Answer:
any of the distinct types of material of which animals or plants are made, consisting of specialized cells and their products
Explanation:
Does this help you?
How is the hfusion used to calculate the energy needed to melt a mass of
solid?
Answer:
You can use fusion to measure the amount of energy required to melt a given amount of a solid at its melting point temperature.
Explanation:
1. Describe the liquid state according to the
kinetic-molecular theory.
Answer:
Liquids have more kinetic energy than solids. When a substance increases in temperature, heat is being added, and its particles are gaining kinetic energy. Because of their close proximity to one another, liquid and solid particles experience intermolecular forces. These forces keep particles close together.
Explanation:
hope it helps U
According to the kinetic theory of gases, an ideal gas molecule
Answer:
According to the kinetic theory of gases, in an ideal gas between two successive collisions, a gas molecule travels in a straight line.
Two compounds might have spots with the same rf value in a chromatography experiment and not be identical compounds. Which proposed chromatography experiment could best help determine whether the compounds are identical?.
The repeat of the original chromatography experiment with a different solvent might could best help determine whether the compounds are identical.
What is chromatography?Chromatography is a technique used in the laboratory to physically separate two different objects and/or materials.
In chromatography, these materials are separated into two phases called the stationary phase and the movement phase.
Chromatography is also used to purify a given substance and thus determine its exact composition.
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In a terrarium, the pincushion moss, the echeveria, and the moon cactus make up which of the following? Select all that apply. A. a population B. part of a community C. part of an ecosystem
The pincushion moss, the echeveria, and the moon cactus in a terrarium make up a community.
What is a community of organisms?A community of organisms refers to a group of organisms of different species which are found living together in the same habitat.
Populations of organisms of different species within the same habitat constitute a community.
The pincushion moss, the echeveria, and the moon cactus are all different species found within the same habitat, a terrarium.
Therefore, the different species of organisms in the terrarium make up a community.
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Answer: part of a community and part of an ecosystem
Explanation:
It's sunny in new york, but it is cool. where would you expect to find this lizard during the day? question 16 options: under a rock in a damp stream bed basking in a sunny spot in a hole in the ground
It's sunny in new york, but it is cool, we will expect to find lizard under a rock or in a hole in the ground.
Why lizards are not comfortable in cold?Lizards are not comfortable in the cold season as they are cold blooded animal, so their body will gets slow in the winter season.
During the winter season or in the cool weather, lizards will go to the places where they faces less cooling. And these places be like inside the rocks, under a hole, under the ground, in the trunks of trees, etc.
Hence, options (1) and (4) are correct.
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