Which is not true of radioactive half-life? radioactive half-life is increased by heating the isotope. independent of the physical or chemical form of the isotope. the time required for the level of radioactivity in a sample to be cut in half. independent of the amount of radioactive material present?
Answer:
"Radioactive half-life is increased by heating the isotope" is not true.
Explanation:
The radioactive half-life is the time required for half of any given amount of a substance (or isotope), to undergo radioactive decay.
This radioactive decay does not depend on the physical form of the substance nor it depends on the temperature.
Which compound has the same empirical and molecular formula ethyne ethene ethane methane?
Recall that your hypothesis is that these values are the fraction of atoms that are still radioactive after n half-life cycles. Record in the appropriate blanks.
Answer : A= 0.5, B = 0.25 , C = 0.125, D = 0.015625 and E = 0.00390625
Explanation :
Half life of a substance is defined as the amount of time taken by the substance to reduce to half of its original amount.
Here n represents the number of half lives.
The amount of substance that remains after n half lives can be calculated using the given formula, [tex] 0.5^{n} [/tex]
So when we have n =1,
Fraction of substance that remains = 0.5¹ = 0.5.
That means after first half life over, the amount of substance that remains is 0.5 times that of original.
Therefore we have A = 0.5
When n = 2, we have 0.5² = 0.25
So when 2 half lives are over, the amount of substance that remains is 0.25 times that of original
Therefore B = 0.25
When n = 3, we have 0.5³ = 0.125
So when 3 half lives are over, the amount of substance that remains is 0.125 times that of original.
Therefore we have C = 0.125
When n = 6 , we have 0.5⁶ = 0.015625
So D = 0.015625
When n = 8, we have 0.5⁸ = 0.00390625
Therefore E = 0.00390625
The values for A, B, C, D and E are 0.5, 0.25, 0.125, 0.015625 and 0.00390625 respectively.
Which energy source has been developed and improved by chemists?
Answer:Explained
Explanation:
The following energy has been developed and improved by chemists
Nuclear energy coal gasgasolineEthanolKerosene PropaneAnything which includes chemical reaction has been developed by chemists to utilize the hidden energy.For example Nuclear energy
If proper reactions and controlled environment is given then a huge amount of energy can be generated from Radioactive elements.
Tritium (31h) is an isotope of hydrogen that is sometimes used to make the hands of watches glow in the dark. the half-life of tritium is 12.3 years. after 49 years, approximately how much of the original tritium remains?
Answer:
6.31%
Explanation:
In order to solve this, you need to use the expression to calculate half life, which is the following:
C = Co e^-t λ (1)
Where:
C: concentration after t has passed
Co: initial concentration
t: time that has passed
λ: lambda which relation half life time
λ this can be calculated with the following expression:
λ = ln2 / t(1/2) (2)
So, let's calculate λ first and then, the concentration. In this case, we will assume that we begin with a concentration at 100%.
The value of lambda is:
λ = ln2 / 12.3
λ = 0.0564
Now, let's use (1) to calculate the concentration after 49 years:
C = 100 e^ (-49 * 0.0564)
C = 100 e^(-2.7636)
C = 6.31 %
And this will be the tritium remaining after 49 years
If the concentration of h uons were to decrease what would happen to the oh ions
What is the molarity of a salt solution that is made from 31.0 grams of ca3(po4)2 placed in a volumetric flask and filled to the 2 liter line with distilled water?
What about uranium room temperature is it "SOLID LIQUID or GAS)?
"if the volume is kept constant, and nothing is added to the reaction mixture, what happens to the partial pressure of nitrogen during the course of the reaction?"
The partial pressure of nitrogen during the reaction if the volume is kept constant and nothing is added to the reaction mixture, then the pressure is decreases.
What is pressure ?Pressure is defined as the force applied perpendicular to an object's surface per unit area over which that force is distributed. Gauge pressure is the pressure in relation to the surrounding atmosphere. Pressure is expressed using a variety of units.
Measuring the pressure of a substance is an important part of the manufacturing process in many industries. Obtaining accurate and meaningful data is critical in determining product quality and consistency. For these reasons, precise sensors are critical in gathering this information.
A pascal is a pressure of one newton per square metre, or one kilogram per metre per second squared in SI base units. For many purposes, this unit is inconveniently small, and the kilopascal (kPa) of 1,000 newtons per square meter is more commonly used.
Thus, The partial pressure of nitrogen during the reaction if the volume is kept constant and nothing is added to the reaction mixture, then the pressure is decreases.
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Bromine dichloride, BrCl2, decomposes to form bromine and chlorine at equilibrium according to the following equation:
2BrCl2(g) + heat ⇌ Br2(g) + 2Cl2(g)
For the following change, how would the reaction shift (toward the products, reactants, or no change)?
The temperature is increased?
When the equilibrium of the decomposition of bromine dichloride is disturbed by increasing temperature, the reaction shifts towards the reactants according to Le Chatelier's principle.
If the temperature is increased for the decomposition of bromine dichloride, BrCl2, the reaction will shift towards the reactants. According to Le Chatelier's principle, if a chemical system at equilibrium experiences a change in concentration, temperature, volume, or pressure, then the equilibrium shifts to counteract the imposed change and re-establish equilibrium. In this endothermic reaction, heat is absorbed to convert BrCl2 into bromine, Br2, and chlorine, Cl2. Therefore, increasing the temperature adds heat to the system, which will shift the equilibrium towards the reactants (BrCl2) to absorb the excess heat.
The smallest piece of a compound that retains characteristics of a compound is
List the information you need to find how many milliliters of a stock solution of 2.00m mgso4 you would need to prepare 100.0 ml of 1.00m mgso4
To determine how many milliliters of a stock solution are needed to prepare a given volume of a diluted solution, one can use the dilution formula 'M1V1 = M2V2’. In this case, you'd need 50.0 ml of the stock solution to prepare 100.0 ml of a 1.00m MgSO4 solution.
Explanation:To find out how many milliliters of a stock solution of 2.00m MgSO4 you would need to prepare 100.0 ml of 1.00m MgSO4, you can use the formula M1V1 = M2V2, where M1 is the molarity of the initial solution, V1 is the volume of the initial solution, M2 is the molarity of the final solution, and V2 is the volume of the final solution.
Firstly, we substitute the given values into the formula. M1 is our initial molarity (2.00m), V1 is what we're trying to find, M2 is our final molarity (1.00m) and V2 is our final volume (100.0 ml). By rearranging the formula, we get V1 = (M2 * V2) / M1.
The calculation step becomes: V1 = (1.00m * 100.0 ml) / 2.00m = 50.0 ml. Therefore, you would need 50.0 milliliters of the stock solution to prepare 100.0 ml of a 1.00m MgSO4 solution.
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Light striking a mirror at a 50° angle will be reflected at an angle _____.
Equal TO 50 degree because angle of incidence is equal to angle of reflection.
Answer:
equal to 50 degress
Explanation:
An aqueous solution of an unknown quantity of a nonelectrolyte solute is found to have a freezing point of −0.58°c.what is the molal concentration of the solution?
Final answer:
The molal concentration of the aqueous solution with a freezing point of -0.58°C is 0.312 mol/kg, calculated using the formula for freezing point depression and the molal freezing-point depression constant for water.
Explanation:
To determine the molal concentration of the solution based on the given freezing point depression, we use the formula ΔTf = Kf × m, where ΔTf is the change in freezing point, Kf is the molal freezing-point depression constant for water, and m is the molality of the solution.
For water, Kf is -1.86°C/m. The change in freezing point (ΔTf) can be calculated as the difference from water's normal freezing point, 0°C, to the solution's freezing point, which is -0.58°C. Thus, ΔTf = 0°C - (-0.58°C) = 0.58°C.
Plugging the values into the equation:
ΔTf = Kf × m
0.58°C = (-1.86°C/m) × m
m = 0.58°C / -1.86°C/m
m = 0.312 mol/kg
Therefore, the molal concentration of the solution is 0.312 mol/kg.
In which substance does phosphorus have a +3 oxidation state
Phosphorus has a +3 oxidation state in tetraphosphorus hexaoxide (P4O6) and phosphorous acid (H3PO3).
Explanation:Phosphorus exhibits different oxidation states in various substances. When it comes to a +3 oxidation state, phosphorus(III) oxide, also known as tetraphosphorus hexaoxide (P4O6), is the substance where phosphorus has a +3 oxidation state. This compound can be formed when white phosphorus is carefully burned in limited oxygen. Additionally, another compound where phosphorus has a +3 oxidation state is phosphorous acid, H3PO3, which can be obtained by the slow dissolution of phosphorus(III) oxide in cold water.
Phosphorus also forms hydrides, such as diphosphorus tetrahydride (H2P-PH2) and tetraphosphorus trisulfide (P4S3), which exhibit phosphorus in atypical oxidation states including the +3 state.
What term refers to the coldest and densest zone, deep below the surface of a lake?
Answer: Hypolimnion
Explanation:
The hypolimnion layer is found in the dense region of lake. It is bottom layer of water in a thermally stratified lake.
This region has lowest oxygen concentration,and it lies below the thermocline.
It is the deepest and coldest layer found in lake. It has very less oxygen and maximum amount of sediments is also found there.
There reaches no light so photosynthesis id not possible there. The temperature there is almost 4 °C throughout the year.
A chart that organizes elements by their chemical properties and increasing atomic number is the
15 POINTS
When calcium forms an ion, what is its charge?
2+
3+
2-
3-
Submarines sometimes make a "pinging" sound to determine the depth of an object in the ocean. This process is called
A. sonar.
B. radar.
C. refraction.
D. diffraction
Seawater has a ph of 8.1. what is the concentration of oh–?
When the pressure that a gas exerts on a sealed container changes from 22.5 psi to psi the temperature changes from 110 c to 65.0 c
Answer:
19.9 psi
Explanation:
Which of the following is NOT true about "yield"? a. The value of the actual yield must be given in order for the percent yield to be calculated. b. The percent yield is the ratio of the actual yield to the theoretical yield. c. The actual yield may be different from the theoretical yield because reactions do not always go to completion. d. The actual yield may be different from the theoretical yield because insufficient limiting reagent was used.
All the provided statements about 'yield' in chemistry are correct. The yield represents the amount of product from a chemical reaction. Percent yield is calculated using actual and theoretical yields, which can differ due to incomplete reactions or limiting reagents.
Explanation:Regarding your question about which statement is not true about 'yield', all of the statements you listed are generally correct. Yield in chemistry refers to the amount of product obtained in a chemical reaction. The theoretical yield is the maximum possible amount of product that can be produced from a given amount of reactants. The actual yield is the amount of product actually produced when the chemical reaction is carried out in an experiment.
The percent yield is the ratio of the actual yield to the theoretical yield, expressed as a percentage (statement b). This value indeed requires knowledge of the actual yield (statement a). Both the actual and theoretical yield can differ due to incomplete reaction or inefficient use of limiting reagents (statement c and d).
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A solution in which the hydroxide-ion concentration is 1x10^-2 is
Consider the reaction below. CO(g) + Cl2(g) « COCl2(g) What is the most likely effect to the forward reaction if there is an increase in pressure on this reaction? The reactant surface area increases. The reaction rate decreases. The reaction is not affected at all. The reaction stops completely.
Answer:
The reaction rate decreases.
Explanation:
Which of the following chemical equations is correctly balanced?
A.) H2 + O2 → H2O
B.) 2 C2H4O + 5 O2 → 4 CO2 + 4 H2O
C.) K2S + I2 → 2 KI + S
D.) CaCO3 + 2 HCl → CaCl2 + 2 CO2 + H2O
Option B and C both are balanced.
A chemical reaction is said to be balanced if all the constituent on the left side of the reaction arrow are equal to right side.
(A) The chemical reaction is as follows:
[tex]H_{2}+O_{2}\rightarrow H_{2}O[/tex]
There are 2 hydrogen atoms and 2 oxygen atoms on left side of the reaction arrow and 2 hydrogen and 1 oxygen on right hand side thus, number of oxygen atoms are not balanced.
Therefore, the above chemical reaction is not balanced.
(B) The chemical reaction is as follows:
[tex]2C_{2}H_{4}O+5O_{2}\rightarrow 4CO_{2}+4H_{2}O[/tex]
There are 4 carbon atoms, 8 hydrogen atoms and 12 oxygen atoms on both side of the reaction arrow thus, the chemical reaction is balanced.
(C) The chemical reaction is as follows:
[tex]K_{2}S+I_{2}\rightarrow 2KI+S[/tex]
There are 2 potassium atoms, 1 sulfur atom and 2 iodine atoms on both side of the reaction arrow thus, it is a balanced chemical reaction.
(D) The chemical reaction is as follows:
[tex]CaCO_{3}+2HCl\rightarrow CaCl_{2}+2CO_{2}+H_{2}O[/tex]
There is 1 calcium atom, 1 carbon atom, 3 oxygen atoms, 2 hydrogen atoms and 2 chlorine atoms on left side of the reaction arrow and 1 calcium atom, 2 chlorine atoms, 2 carbon atoms, 5 oxygen atoms and 2 hydrogen atoms on right hand side of the reaction arrow. Thus, number of carbon and oxygen atoms are not balanced in the chemical reaction.
A balanced chemical reaction has the same and a balanced number of stoichiometry coefficients. Option B. [tex]\rm 2 C_{2}H_{4}O + 5 O_{2} \rightarrow 4 CO_{2} + 4 H_{2}O[/tex] and option D. [tex]\rm K_{2}S + I_{2} \rightarrow 2 KI + S[/tex] are balanced equations.
What is a balanced chemical reaction?A balanced chemical reaction is the equated reaction and depiction of the chemical reactants and the products of the reaction. They have balanced stoichiometry coefficients on the left and the right side of the reaction.
In the second reaction, [tex]\rm 2 C_{2}H_{4}O + 5 O_{2} \rightarrow 4 CO_{2} + 4 H_{2}O[/tex], the number of carbon atoms are four on both sides, 8 atoms of hydrogen on both sides and 12 atoms of oxygen balanced on both sides of the chemical reaction.
In the third reaction, [tex]\rm K_{2}S + I_{2} \rightarrow 2 KI + S[/tex], 2 atoms of potassium, 2 atoms of iodine and 1 atom of sulphur is balanced.
Therefore, reactions B and D are balanced reactions.
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Identify the brønsted base in the forward reaction hpo2− 4 (aq) + hno3(aq) ⇀↽ no− 3 (aq) + h2po− 4 (aq). 1. h2po− 4 (aq) 2. hno3 3. hpo2− 4 4. no− 3
The Brønsted base in the forward reaction HPO4²-(aq) + HNO3(aq) ⇀↽ NO3¯ (aq) + H2PO4¯ (aq) is HPO4²-(aq) because it accepts a proton in this reaction.
Explanation:To identify the Brønsted base in the reaction HPO4²-(aq) + HNO3(aq) ⇀↽ NO3¯(aq) + H2PO4¯(aq), let's recognize the definitions of a Brønsted-Lowry base and acid.
A Brønsted base is a proton (H+) acceptor, whereas a Brønsted acid is a proton donor. In the forward reaction, HNO3 donates a proton; making it the Brønsted acid. The species that accepts the proton is HPO4²-. Therefore, HPO4²- is the Brønsted base in the forward reaction of this equilibrium.
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In the reaction, HPO₄²⁻ is the Brønsted base as it accepts a proton from HNO₃. HNO₃ acts as the Brønsted acid. Therefore, option 3: HPO₄²⁻ is correct.
In the forward reaction HPO₄²⁻ (aq) + HNO₃ (aq) ⇄ NO₃⁻ (aq) + H₂PO₄⁻ (aq), we need to identify the Brønsted base.
A Brønsted base is defined as a substance that can accept a proton (H⁺). In this reaction:
HPO₄²⁻ is acting as a Brønsted base because it accepts a proton from HNO₃ to form H₂PO₄⁻. HNO₃ acts as a Brønsted acid since it donates a proton.So, the correct answer is option 3: HPO₄²⁻.
Complete Question.
Identify the Brønsted base in the forward reaction HPO₄²⁻ (aq) + HNO₃(aq) ⇄ NO₃⁻ (aq) + H₂P0₄⁻ (aq).
1. NO₃⁻
2. H₂PO₄⁻ (aq)
3. HPO₄²⁻
4. HNO₃
Which acid dissociation constant (ka indicates the weakest acid? 8.5 × 10–3m 1.5 × 10–10m 3.5 × 10–7m 5.1 × 10–5m?
A group of chemistry students had to identify six white powders. The students used a variety of tests to identify the powders. They computed the density of each powder. They checked to see if any dissolved in water. One of the powders did not dissolve in water and they thought it was cornstarch. Someone knew that cornstarch felt slippery and reacted with iodine. The students put a few drops of iodine on each white powder. One powder turned black; they guessed that it was cornstarch. They heated the powders in a Bunsen burner flame to see if any would melt. One did and they guessed it might be a sugar. Which test result indicated a chemical change had taken place? A) dissolves in water B) feels slippery in water C) melts when heated in a flame D) turns black when iodine is added
What volume of 0.45 M LiOH would be needed to neutralize 60.0 mL of 0.15 M Hi?
To neutralize 60.0 mL of 0.15 M HCl, 20.0 mL of 0.45 M LiOH is required. The neutralization reaction proceeds in a 1:1 molar ratio.
Explanation:To calculate the volume of 0.45 M LiOH required to neutralize 60.0 mL of 0.15 M HCl, we use the neutralization reaction where LiOH reacts with HCl in a 1:1 molar ratio:
LiOH + HCl → LiCl + H2OFirst, calculate the number of moles of HCl:
moles HCl = volume (L) × molarity (M) = 0.060 L × 0.15 M = 0.009 moles
Since the molar ratio is 1:1, 0.009 moles of LiOH will also be needed.
Then, calculate the volume of LiOH solution:
Volume LiOH = moles LiOH / molarity of LiOH = 0.009 moles / 0.45 M = 0.020 L or 20.0 mL
Therefore, 20.0 mL of 0.45 M LiOH is required to neutralize 60.0 mL of 0.15 M HCl.
What is the result of mixing the two substances shown here together?
They are not attracted to each other because one is polar and one is nonpolar — is the correct answer