Answer:
True
Explanation:
A chemical change is otherwise known as a chemical reaction. A chemical change is characterized by the formation of new substances, evolution of heat and change in chemical composition of substances. The change in the composition of substances during a chemical change is the result of the making and breaking of chemical bonds during a chemical change.
A chemical change is not easily reversible because it involves changes in chemical composition of substances.
An example of a chemical change is the combination of sodium hydroxide and hydrochloric acid according to the reaction equation;
HCl(aq) + NaOH (aq) -----> NaCl(aq) + H2O (l)
We easily notice the change in the chemical composition of each of the substances involved in the reaction.
Which part of the stem transports water to the rest of the plant? A.root cells b. xylem c.bark d. phloem
Answer:
B
Explanation:
Answer:
xylem
Explanation:
Which is a saturated solution?
A）40g NH4Cl in 100g water at 50°C
B）2g SOz in 100g water at 10°C
C）52g KCl in 100g water at 80°C
D）120g KI in 100g water at 20°C
Answer:
C）52g KCl in 100g water at 80°C
Explanation:
A saturated solution is one that contains as much solute as it can dissolve in the presence of excess solute at that particular temperature.
A solutibility curve is a graph that shows the variability with temperature of the solubility of a solute in a given solvent. A solutibility curve can provide information of whether a solution formed frommthe solute and solvent are saturated or not at a given temperature.
From the solubility curve in the attachment below:
A) A saturated solution of NH₄Cl will contain about 52 g solute per 100 g sat 50 °C. Thus, a solution of 40 g NH₄Cl in 100 g water at 50 °C is an unsaturated solution.
B) A saturated solution of SO₂ at 10°C will contain about 70 g of solute in 100 g of water. Thus a solution of 2g SO₂ in 100g water at 10°C is an unsaturated solution.
C) A saturated solution of KCl at 80 °C will contain about 52 g of solute in 100 g of water. Thus, a solution of 52g KCl in 100g water at 80°C is a saturated solution.
D) A saturated solution of Kl at 20 °C will contain about 145 g of solute in 100 g of water. Thus, a solution of 120g KI in 100g water at 20°C is an unsaturated solution.
what is a mole and its properties
One mole of a substance is equal to 6.022 × 10²³ units of that substance (such as atoms, molecules, or ions). The number 6.022 × 10²³ is known as Avogadro's number or Avogadro's constant. The concept of the mole can be used to convert between mass and number of particles.
In order to determine the answer to a chemistry problem, a student first converted the given percentages to mole by assuming the sample size was 100 grams. Then the student divide by the smallest mole amount of the elements present. Finally the student used the ratios to write a formula. Which of the following best describes the problem the student likely solved?
a. Determined percent composition
b. None of the above
c. Determining molecular formula
d. Determining empirical formula
Answer: d. Determining empirical formula
Explanation:
Molecular formula is the chemical formula which depicts the actual number of atoms of each element present in the compound.
Empirical formula is the simplest chemical formula which depicts the whole number of atoms of each element present in the compound.
Step 1: If percentage are given then we are taking total mass is 100 grams. So, the mass of each element is equal to the percentage given.
Step 2 : convert given masses into moles
Step 3 : For the mole ratio, divide each value of moles by the smallest number of moles calculated
Step 4: The mole ratio gives the empirical formula of the compund.
Describe how chemical reactions are affected by reaction conditions
of monction?
Answer:
hope his helps
Explanation:
Mention the factors affecting the rate of reaction
There are four main factors that can affect the reaction rate of a chemical reaction:
Reactant concentration. Increasing the concentration of one or more reactants will often increase the rate of reaction. ...
Physical state of the reactants and surface area. ...
Temperature. ...
Presence of a catalyst.
Balance the chemical equation below using the smallest possible whole number stoichiometric coefficients.
The balanced chemical equation using the smallest possible whole number stoichiometric coefficients is:
[tex]3Br_{2} + I_{2} \rightarrow 2IBr_{3}[/tex]
What is a balanced equation?A balanced chemical equation is an equation in which the the moles of atoms in of elements of reactants is equal to mole of atoms of elements of the product.
The balanced chemical equation of the reaction is given below:
[tex]3Br_{2} + I_{2} \rightarrow 2IBr_{3}[/tex]
Therefore, the balanced chemical equation using the smallest possible whole number stoichiometric coefficients is given above.
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Solution remained colorless.
During the experimentation, the test tube was gently heated in a Bunsen burner flame for 60 seconds. What was the reason for this specific
procedure?
A)
Heating was done to initiate the combustion of the metal in water.
B)
Heating was done to confirm that no chemical reaction would take
place in acid
0
Heating was done to precipitate the chemical change in each test
tube containing water
D)
Heating helped released the hydrogen contained in water
molecules so students would have a positive H+ test.
________ exercise strengthens skeletal muscle, and ________ exercise strengthens skeletal and cardiac muscle.
a.resistance, aerobic
c.
aerobic, resistance
b.
aerobic, aerobic
d.
resistance, resistance
Answer:
... :-!...................nose...........Give the reason for the following; 1. Iodimetric titrations are usually performed in neutral or mildly alkaline (pH 8) to weakly acid solution. 2. Iodine solutions are prepared by dissolving I2 in a concentrated solution of potassium iodide. 3. Iodimetric determination of vitamin C is performed rapidly after preparing vitamin C solution
Answer:
Explanation:
blach bal
when forces act in equal and opposite directions the net force is and the object
Answer:
Equal forces acting in opposite directions are called balanced forces. Balanced forces acting on an object will not change the object's motion. When you add equal forces in opposite direction, the net force is zero.
Explanation:
Rank the following compounds in order of increasing solubility in water. Items (4 items) (Drag and drop into the appropriate area) No more items Items in order most soluble CaO BaO KCI KI
I have tried CaO> BaO > KCl > KI, this is incorrect.
Answer:
CaO < BaO < KCl <KI
Explanation:
Let us remember that the solubility of an ionic substance in water depends on the magnitude of the lattice energy and the hydration energy. If the hydration energy is equal to or is greater than the lattice energy, the substance dissolves in water.
However, the lattice energy depends on the size of the ions. The smaller the ions in the ionic compound, the higher the lattice energy and the lesser the solubility of the ionic compound.
KI has the least lattice energy and the highest solubility in water while CaO has the highest lattice energy and the least solubility in water.
1,3,5,7-Cyclooctatetraene, C8H8, is an unusual hydrocarbon in that it reacts with exactly 2 equivalents of potassium to give A, C8H8K2, which can be isolated as a white solid. A exhibits a single proton NMR signal. Draw the structure of A
Answer:
Explanation:
The main assignment here is to provide the structure of A. But before that, let us explain briefly some certain things:
The proton NMR (1H) gives data about the quantity of non-identical protons present in the structure. The resonance frequency is seen regarding the standard compound (0 ppm), which is addressed as a chemical shift. The same protons have equal value of chemical shift.
The protons that are available in a similar environment are addressed as comparable protons and the protons with various conditions are called non-identical protons.
However, from the image below, we can see the reaction of the compound 1,3,5,7-cyclooctatetraene resulting in 2 equivalents of potassium forming an aromatic dianion.
A chemistry student is given 4.00 L of a clear aqueous solution at 22°C. He is told an unknown amount of a certain compound X is dissolved in the solution. The student allows the solution to cool to 22 C. The solution remains clear. He then evaporates all of the water under vacuum. A precipitate remains. The student washes, dries and weighs the precipitate. It weighs 0.56 kg.
Required:
Using only the information above, Calculate the solubility of X in water at 22° C. If you said yes, calculate it Be sure your answer has a unit symbol and 2 no .0 it. significant digits.
Answer:
The responses to the given points can be defined as follows:
Explanation:
In point 1:
The answer is "No".
In point 2:
The mass of solute = The mass of precipitate [tex]= 0.56\ kg =0.56\ \times 1000 = 560 \ g[/tex]
Calculating the solubility:
[tex]= \frac{\text{mass of solute in g}}{\text{volume of solution in ml}}\\\\ = \frac{560}{ 4000} \\\\ = 0.14 \ \frac{g}{ml}[/tex]
2H2O ---> 2H2O + O 2
How many moles of chlorine atoms are there in 0.5 mol of titanium (III) chloride?
Answer:
it is your answer..... if it is helpful plzz like and comment.....
Which contains the greatest number of moles of oxygen atoms?
Answer:
B. OR C.
Explanation:
So, 1 mol of ethanol, C2H5OH contains 1 mol of atoms of O; 1 mol of formic acid, HCO2H contains 2 moles of atoms of O; and 1 mol of water, H2O contains 1 mol of atoms of O.
Answer: So, of the three compounds given, formic acid, HCO2H, contains the greatest number of moles of oxygen atoms.
HELP FAST 75 PTS Calculate the amount of heat needed to melt 35.0 g of ice at 0 ºC. must show work
Answer:
It takes 12,000 Joules of energy to melt 35 grams of ice at 0 °C
Explanation:
Good Luck!
5. A grouping of organisms based on shared characteristics is called
A. binomial nomenclature
B. scientific name
C. classification
D. genus
Answer:
peace of vassals
Explanation:
I think i spelled it worng
ould it make any difference if the methylene chloride solutioncontaining both thebasicand neutral components waswashed with 1Msodium hydroxiderather than 1Mhydrochloric acid? If so,what would that difference be? Would any layer separation bepossible in the new solution? Would it be possible to isolate the two components from oneanother using 1Msodium hydroxiderather than 1Mhydrochloric acid?Why or why not?Provide a balanced equation to justify your answ
Answer:
Explanation:
No, it is ludicrous and not possible to separate and detach a basic and neutral compound by 1M NaOH in DCM. This is due to the fact that neutral compounds don't respond and react with NaOH, and NaOH itself occurs to be a base. As a result, it can't respond and react with another base to produce salt. Consequently, we simply need a corrosive component i.e an acid
So; In DCM, we can't use 1M NaOH instead of 1M HCI for isolation and separation of neutral and basic compound mixtures.
what makes up the cell menbrane
With few exceptions, cellular membranes — including plasma membranes and internal membranes — are made of glycerophospholipids, molecules composed of glycerol, a phosphate group, and two fatty acid chains. Glycerol is a three-carbon molecule that functions as the backbone of these membrane lipids.
Explanation:
the principal components of plasma membrane are lipids phospholipid and cholesterol proteins and carbohydrates
i
CH3-CH2-CO-CH2-CH2-CH3 + H2
Pd
Answer:
i don't know but I just want to have coins
This timeline woulchre useful to someone who was writing a report titled
HELPPPPPPPPPPPPPPPPP
Answer:
[tex]2H_{2} + O_{2} --> 2H_{2} O[/tex]
Explanation:
This balanced equation satisfies the law of conservation of mass because when balanced with the proper coefficients (the large numbers appearing to the left of each element or compound), there are the same number and type of atoms on each side. There are four hydrogen atoms and two oxygen atoms in both the reactants and the products.
Which law of thermodynamics? Defines what thermal equilibrium is.
2nd
1st
0th
Answer:
0th
Explanation:
he laws of thermodynamics define a group of physical quantities, such as temperature, energy, and entropy, that characterize thermodynamic systems in thermodynamic equilibrium. The laws also use various parameters for thermodynamic processes, such as thermodynamic work and heat, and establish relationships between them. They state empirical facts that form a basis of precluding the possibility of certain phenomena, such as perpetual motion. In addition to their use in thermodynamics, they are important fundamental laws of physics in general, and are applicable in other natural sciences.
Traditionally, thermodynamics has recognized three fundamental laws, simply named by an ordinal identification, the first law, the second law, and the third law.[1][2][3] A more fundamental statement was later labelled as the zeroth law, after the first three laws had been established.
why iodide ions cannot be determined by Mohr method
Answer:
Exactly the same approach can be used for determination of bromides. Other halides and pseudo halides, like I- and SCN-, behave very similarly in the solution, but their precipitate tends to adsorb chromate anions making end point detection difficult.
Hope it helps!
Mohr method is the titration method, used for the determination of the chloride ion concentration in solution. It can not be used for iodine ions, as the alkaline titration is not suitable for iodine.
What is titration?Titration is the analytical process used for the determination of the concentration of a compound, by reacting it with titrant.
The mohr method is the titration method, that determines the concentration of the cations in the solution by titrating them with the salt. The salt formed precipitate in the reaction and the end point is determined.
The limitation to the use of mohr method, is its inability for the analysis of the chlorides of cations, as the reaction is carried out at high pH in alkaline conditions.
The iodide slats are suitably precipitated in the alkaline solution, and thus limits the use of the mohr method.
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What happens to the pH when alkali is added to the distilled water?
Adding water to an acid or base will change its pH. ... The acid is becoming less acidic. Similarly, when an alkali is diluted with water the concentration of OH - ions decreases. This causes the pH of the alkali to fall towards 7, making the solution less alkaline as more water is added
Alkali is a chemical that is characterized by reacting with acids to produce salts. When alkali or base are added to the distilled water then pH increases.
What is pH?
The pH has been defined as the concentration of the hyronium or the hydrogen ions that releases when dissolved in water. The concentration of the hydroxide and the hydrogen are the determining factor of the acidic and basic nature.
The acids are characterized by the low pH (below 7) whereas, the basic compounds are characterized by the high pH (above 7). The pH scale is used to measure the pH of the solution.
When an alkali is added to the distilld water then hydroxide ions are relesed resulting in an increase in the basicity of the water sample. The pH range depends on the strong and weak base.
Therefore, the pH increases after ading alkaline solution.
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A helium nucleus with two protons and two neutrons is called a(n)
A. alpha particle
B. beta particle
C. electroscope
D. gamma ray
Clear selection
Answer:
Explanation:
Alpha particles,
What are the types of forces involved in the production of hydro-electricity
Answer:
There are three types of hydropower facilities: impoundment, diversion, and pumped storage. Some hydropower plants use dams and some do not. The images below show both types of hydropower plants.
Explanation:
Please help me as soon as possible!!! How many grams of H3PO4 are in a 4 L sample of a 17 M solution?
Answer:
about 6664 grams of hydro phosphoric acid are in a sample of 4 L of 17 M solution
Explanation:
grams of H3PO4 = 4 L | 17 mol | 98 grams H3PO4
| 1 L | 1 mol
5
Select all the correct answers.
Which sentences describe chemical changes?
The temperature of water rises when heated.
When mixed, water and limestone give off heat.
A mixture of red paint and green paint becomes black.
On adding yellow turmeric to a transparent soap solution, the mixture turns bright red.
When ground into powder, grains of wheat become flour.
Answer: The answers are:
When mixed, water and limestone give off heat.
On adding yellow turmeric to a transparent soap solution, the mixture turns bright red.