Answer:
An endothermic reaction is one that absorbs energy in the form of heat or light. ... This is why we burn fuels (such as paraffin, coal, propane and butane) for energy, because the chemical changes that take place during the reaction release huge amounts of energy, which we then use for things like power and electricity.
Explanation:
Many endothermic reactions helps us i our daily life.
Combustion reactions
The burning of fuel is an example of a combustion reaction, and we as humans rely heavily on this process for our energy requirements. The following equations describe the combustion of a hydrocarbon such as petrol :
fuel + oxygen heat + water + carbon dioxide
This is why we burn fuels (such as paraffin, coal, propane and butane) for energy, because the chemical changes that take place during the reaction release huge amounts of energy, which we then use for things like power and electricity. You should also note that carbon dioxide is produced during this reaction. The chemical reaction that takes place when fuels burn has both positive and negative consequences. Although we benefit from heat, power and electricity the carbon dioxide that is produced has a negative impact on the environment.
Lightsticks or glowsticks are used by divers, campers, and for decoration and fun. A lightstick is a plastic tube with a glass vial inside it. To activate a lightstick, you bend the plastic stick, which breaks the glass vial. This allows the chemicals that are inside the glass to mix with the chemicals in the plastic tube. These two chemicals react and release energy. Another part of a lightstick is a fluorescent dye which changes this energy into light, causing the lightstick to glow! This is known as phosphorescence or chemiluminescence.
The U.S. requires automobile fuels to contain a renewable component. The fermentation of glucose from corn produces ethanol, which is added to gasoline to fulfill this requirement: C6H12O6(s) → 2 C2H5OH(l) + 2 CO2(g) Calculate ΔH o , ΔS o and ΔG o for the reaction at 25°C. Is the spontaneity of this reaction dependent on temperature? ΔH o rxn = kJ ΔS o rxn = J/K ΔG o rxn = kJ
The reaction is:
spontaneous at all temperatures
nonspontaneous at all temperatures
spontaneous only at high temperatures
spontaneous only at low temperatures
spontaneous only in the reverse direction
Answer:
ΔH° = -67.9 kJ
ΔS° = 536.7 J/K = 0.5367 kJ/K
ΔG° = -227.8 kJ
the reaction is spontaneous at all temperatures
Explanation:
Step 1: Data given
Temperature = 25.0 °C
ΔH°f(glucose) = - 1274.5 kJ/ mol
ΔH°f(C2H5OH) = -277.7 kJ/mol
ΔH°f(CO2) = -393.5 kJ/mol
S°(glucose) = 212.1 J/ K)
S°(C2H5OH) = 160.7 J/K
S°(CO2) = 213.7 J/K
Step 2: The balanced equation
C6H12O6(s) → 2 C2H5OH(l) + 2 CO2(g)
Step 3: Calculate ΔH°
ΔH° = 2*ΔH°f(C2H5OH) + 2ΔH°f(CO2) - ΔH°f(glucose)
ΔH° = 2*(-277.7 kJ) + 2*(-393.5 kJ) - (-1274.5 kJ)
ΔH° = -555.4 kJ + (-787 kJ) +1274.5 kJ)
ΔH° = -67.9 kJ
Step 4: Calculate ΔS°
ΔS° = 2*S°(C2H5OH) + 2*S°(CO2) - S°(glucose)
ΔS° = 2*(160.7 J/K) + 2(213.7 J/K) - 212.1 J/K
ΔS° = 321.4 + 427.4 J/K - 212.1 J/K
ΔS° = 536.7 J/K = 0.5367 kJ/K
Step 5: Calculate ΔG°
ΔG° =ΔH° - T*ΔS°
ΔG° = -67.9 kJ - 298K * 0.5367 kJ/K
ΔG° = -227.8 kJ
Since ΔS° is positive and ΔH° is negative, ΔG° will be negative
This means ΔG° is negative at all temperature.
A negative ΔG° means the reaction is spontaneous at all temperatures
a) ΔH° = -67.9 kJ
b) ΔS° = 536.7 J/K = 0.5367 kJ/K
c) ΔG° = -227.8 kJ
The reaction is spontaneous at all temperatures
What information do we have?
Temperature = 25.0 °C
ΔH°f(glucose) = - 1274.5 kJ/ mol
ΔH°f(C₂H₅OH) = -277.7 kJ/mol
ΔH°f(CO₂) = -393.5 kJ/mol
S°(glucose) = 212.1 J/ K
S°(C₂H₅OH) = 160.7 J/K
S°(CO₂) = 213.7 J/K
Balanced chemical equation:[tex]C_6H_{12}O_6(s) --- > 2 C_2H_5OH(l) + 2 CO_2(g)[/tex]
Calculation of ΔH°:
ΔH° = 2*ΔH°f(C₂H₅OH) + 2ΔH°f(CO₂) - ΔH°f(glucose)
ΔH° = 2*(-277.7 kJ) + 2*(-393.5 kJ) - (-1274.5 kJ)
ΔH° = -555.4 kJ + (-787 kJ) +1274.5 kJ)
ΔH° = -67.9 kJ
Calculation of ΔS°:
ΔS° = 2*S°(C₂H₅OH) + 2*S°(CO₂) - S°(glucose)
ΔS° = 2*(160.7 J/K) + 2(213.7 J/K) - 212.1 J/K
ΔS° = 321.4 + 427.4 J/K - 212.1 J/K
ΔS° = 536.7 J/K = 0.5367 kJ/K
Calculation of ΔG°:
ΔG° =ΔH° - T*ΔS°
ΔG° = -67.9 kJ - 298K * 0.5367 kJ/K
ΔG° = -227.8 kJ
Since, ΔS° is positive and ΔH° is negative, ΔG° will be negative,
ΔG° is negative at all temperatures.
A negative ΔG° means the reaction is spontaneous at all temperatures.
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An isotope has the same number of______but a different number of____than other atoms of the same element. :)
Answer:
an isotope has the same number of protons but a different number of neutrons than the other atoms of the same element.
An isotope has the same number of protons but a different number of neutrons than other atoms of the same element.
What is an isotope?An isotope is one of two or more forms or types of the same or identical chemical element of the periodic table depending on the number of electrons of the element. Some of them become radioactive too if we isolate the proton from the nucleus.
The different isotopes of an element are the same in the number of protons in the nucleus of an atom giving them the identical atomic number, but a different number of neutrons of the element of the isotope contains a different atomic weight.
Therefore, the isotope has the same number of protons but a different number of neutrons than other atoms of the same element.
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A mixture with medium sized particles that do not settle out is called
Answer: colloid
Explanation:
Colloids are solutions in which small sized particles are suspended throughout the solution as they do not settle own their own. Colloids are defined as the mixtures where the size of the particle is within the range of 2nm to 1000 nm. In these mixtures, physical boundary is seen between the dispersed phase and dispersed medium.
Colloids are solutions with particle size intermediate between true solutions and suspensions. Suspensions have large sized particles which settle when left undisturbed for sometime and thus can be filtered off easily. The particle size in colloids is less and hence they do not settle under the effect of gravity.
A student was given two clear liquids; a colorless liquid and a dark-blue liquid. The student was asked to combine the liquids in a beaker and record observations. Which of the following results, if true, would provide the best evidence that a chemical change took place when the liquids were combined?
a) The resulting mixture was cloudy.
b) The total volume of the mixture was equal to the sum of the initial volumes.
c) The resulting liquid was light blue.
d) The liquids formed two separate layers in the beaker.
Answer:
The correct option is;
a) The resulting mixture was cloudy
Explanation:
Here we have the initial color as
1. Colorless and
2. Dark blue
We analyze each of the results as follows
a) The resulting mixture was cloudy
A cloudy mixture forming when the two liquids are mixed is most likely due to the formation of a suspension from a new substance That is a new compound is formed
b) The total volume of the mixture was equal to the sum of the initial volumes.
Here since there is no change in the physical properties as the volume of the mixture is the sum of the volumes of the constituent then there is unlikely to be a chemical change
c) The resulting liquid was light blue
Here, the observation is more of a physical change
d) The liquids formed two separate layers in the beaker.
This is an indication that there was no mixing of the liquids hence no reaction or chemical change.
Final answer:
The best evidence of a chemical change after mixing two liquids, based on the given options, is c) The resulting liquid was light blue, indicating that a new substance with a different color has been formed.
Explanation:
The question pertains to determining whether a chemical change has occurred upon mixing two liquids. Observations that typically indicate a chemical change include unexpected color changes, formation of a precipitate, temperature changes, light emission, bubbles (especially if the substance is not boiling), and different smells. In the context of the given choices, the best evidence of a chemical change is c) The resulting liquid was light blue.
Choice a) could simply be due to the scattering of light and does not necessarily indicate a chemical change. Choice b) is characteristic of a physical change where volumes are additive and no new substances are formed. Choice d) suggests immiscibility rather than a chemical reaction. However, choice c) suggests that a new substance with a different color has been formed, which is a strong indicator of a chemical reaction. A direct combination of a colorless and a dark-blue liquid would not result in a light-blue liquid unless there was a change in composition, which leads us to conclude that a chemical change has taken place.
What condition of the gas remains constant?
Answer:
The temperature remains constant because the internal energy only depends on temperature in that case
-Hops
An acidic solution at 25°c will have a hydronium ion concentration ________ and a ph value ________.
An acidic solution at 25°C has a hydronium ion concentration greater than 1.0 × 10⁻⁷ M and a pH less than 7.00.
An acidic solution at 25°C will have a hydronium ion concentration greater than 1.0 × 10⁻⁷ M and a pH value less than 7.00. This is because in an acidic solution, the concentration of H₃O+ (hydronium ions) exceeds that of OH- (hydroxide ions). The pH of a solution is calculated using the formula pH = -log[H₃O+]. Therefore, if the concentration of hydronium ions is higher than 1.0 × 10⁻⁷ M, the negative logarithm of this concentration will yield a pH value less than 7.00.
Compound a reacts with one equivalent of h2 in the presence of a catalyst to give methylcyclohexane. Compound a can be formed upon treatment of 1-bromo-1-methylcyclohexane with sodium methoxide. What is the structure of compound a?
Answer:
The compound a is 1-methyl cyclohexene (see attachment for structure).
Explanation:
The reaction of 1-Bromo-1-methylcyclohexane with sodium methoxide is a second-order reaction since the methoxide ion is a strong base and also a strong nucleophile. This ion attacks the alkyl halide faster than the alkyl halide can ionize to produce a first-order reaction. However, we can not see the product of nucleophilic substitution. The SN₂ mechanism is blocked due to the impediment of the 1-Bromo-1-methylcyclohexane. The main product, according to the Zaitsev rule, is the 1-methyl cyclohexene, thus forming a double bond.
Then, this cyclohexene is hydrogenated to form the cyclohexane.
Final answer:
Compound A is formed when 1-bromo-1-methylcyclohexane is treated with sodium methoxide. The structure of compound A is methylcyclohexane with a methoxy group attached to one of the carbon atoms.
Explanation:
The structure of compound A can be determined by considering the reactions and information given in the question. Compound A is formed when 1-bromo-1-methylcyclohexane is treated with sodium methoxide. This reaction suggests that the bromine atom in 1-bromo-1-methylcyclohexane is replaced by a methoxy group (-OCH3) to form compound A. Therefore, the structure of compound A is methylcyclohexane with a methoxy group attached to one of the carbon atoms.
Which letter (a-f) represents activation energy (Ea) of the forward reaction (reactants)?
Which letter (a-f) represents activation energy (Ea) of the reverse reaction (products)?
Answer:
The correct option is;
f
Explanation:
Here we have the activation energy is the minimum energy that is needed to allow a reaction to take place. The activation energy is the energy atoms or molecules need to be in a state where they can take part in a chemical reaction or a physical transport.
In the diagram, It is the amount of energy to be added to the energy in the reactants in their initial state which is on the left plateau on the reaction-energy chart, to the transition state which is the peak of the chart.
Is nh4co3 soluble in water?
Answer:
yes
Explanation:
Answer:
Water
Ammonium nitrate/Soluble in
Ammonium Carbonate is water-soluble and decomposes in hot water.
Explain how you would determine the number of grams of Cu(NO3)2 that would be needed to make 1052 mL of a 2.50 M solution of Cu(NO3)2
Answer:
The answer to your question is 493.31 grams
Explanation:
Data
mass of Cu(NO₃)₂ = ?
volume = 1052 ml
concentration = 2.50 M
Process
1.- Write the formula to determine the Molarity
Molarity = moles/volume
-Solve for moles
moles = Molarity x volume
-Substitution
moles = 2.50 x 1.052
-Result
moles = 2.63
2.- Calculate the molar mass of Cu(NO₃)₂
Cu(NO₃)₂ = (63.55 x 1) + (14.01 x 2) + (16 x 6)
= 63.55 + 28.02 + 96
= 187.57 g
3.- Calculate the grams of Copper nitrate
187.57 g -------------------- 1 mol
x -------------------- 2.63 moles
x = (2.63 x 187.57) / 1
x = 493.31 / 1 grams
x = 493.31 grams
Of four different laboratory solutions, the solution with the highest acidity has a pH of ___. *
11
7
5
3
The solution with the highest acidity has a pH of 3.
What is pH?pH of any solution tells about the acidity or basicity of that solution.
pH scale ranges from 0 to 14, where 7 shows the neutrality of the solution and values below 7 express the acidity and above 7 express the basicity of the solution.
So, lower value of pH shows the high acidity of the solution.
Hence, option (4) is correct i.e. 3 shows the highest acidity.
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If I initially have a gas at a pressure of 12 atm, a volume of 23 liters, and a temperature of 200 K and then I raise the pressure to 14 atm and increase the temperature to 300 K, what is the new volume of gas
Answer:
The answer to your question is V2 = 29.6 l
Explanation:
Data
Pressure 1 = P1 = 12 atm
Volume 1 = V1 = 23 l
Temperature 1 = T1 = 200 °K
Pressure 2 = 14 atm
Volume 2 = V2 = =
Temperature 2 = T2 = 300°K
Process
1.- To solve this problem use the Combine gas law.
P1V1/T1 = P2V2/T2
-Solve for V2
V2 = P1V1T2 / T1P2
2.- Substitution
V2 = (12)(23)(300) / (200)(14)
3.- Simplification
V2 = 82800 / 2800
4.- Result
V2 = 29.6 l
LU
Calculating Kinetic Energy
A conveyer belt moves a 40 kg box at a velocity of 2 m/s. What is the kinetic energy of the box while it is on the
conveyor belt?
40J
803
160J
1,600
Answer:
80joules
Explanation:
1/2mv²
1/2x40x2²
1/2x40x4
1/2x160
=80joules
how many moles are there of a 7m solution with a volume of 14.44 liters
Answer:
The answer to your question is 101.08 moles
Explanation:
Data
number of moles = ?
concentration = 7 M
volume = 14.44 l
Process
1.- Write the Molarity formula
Molarity = moles / volume
2.- Solve for moles
moles = Molarity x volume
3.- Substitution
moles = 7 x 14.44
4.- Result
moles = 101.08
The functional unit of the kidney is the ______
Answer:
The nephron
Explanation:
is responsible for removing waste from the body.
For scuba dives below 150 ft, helium is often used to replace nitrogen in the scuba tank. If 15.2 g of He(g) and 30.6 g of O2(g) are added to a previously evacuated 5.00 L tank at 22° C, calculate the partial pressure of each gas present as well as the total pressure in the tank.
Answer:
see explanation below
Explanation:
To do this exercise, we need to use the following expression:
P = nRT/V
This is the equation for an ideal gas. so, we have the temperature of 22 °C, R is the gas constant which is 0.082 L atm / mol K, V is the volume in this case, 5 L, and n is the moles, which we do not have, but we can calculate it.
For the case of the oxygen (AW = 16 g/mol):
n = 30.6 / 32 = 0.956 moles
For the case of helium (AW = 4 g/mol)_
n = 15.2 / 4 = 3.8 moles
Now that we have the moles, let's calculate the pressures:
P1 = 0.956 * 0.082 * 295 / 5
P1 = 4.63 atm
P2 = 3.8 * 0.082 * 295 / 5
P2 = 18.38 atm
Finally the total pressure:
Pt = 4.63 + 18.38
Pt = 23.01 atm
The partial pressures are [tex]\( P_{\text{He}} = 18.40 \, \text{atm} \)[/tex], [tex]\( P_{\text{O}_2} = 4.63 \, \text{atm} \)[/tex]. The total pressure in the tank is [tex]\( P_{\text{total}} = 23.03 \, \text{atm} \)[/tex].
To calculate the partial pressure of each gas and the total pressure in the tank, we will use the ideal gas law, [tex]\( PV = nRT \)[/tex], where [tex]\( P \)[/tex] is the pressure, [tex]\( V \)[/tex] is the volume, [tex]\( n \)[/tex] is the number of moles, [tex]\( R \)[/tex] is the ideal gas constant, and [tex]\( T \)[/tex] is the temperature in Kelvin.
First, convert the temperature from Celsius to Kelvin:
[tex]\[ T = 22^\circ \text{C} + 273.15 = 295.15 \text{ K} \][/tex]
The ideal gas constant [tex]\( R \)[/tex] is [tex]\( 0.0821 \, \text{L} \cdot \text{atm} \cdot \text{mol}^{-1} \cdot \text{K}^{-1} \)[/tex].
Next, calculate the number of moles of each gas:
1. Helium (He):
[tex]\[\text{Molar mass of He} = 4.00 \, \text{g/mol}\][/tex]
[tex]\[n_{\text{He}} = \frac{15.2 \, \text{g}}{4.00 \, \text{g/mol}} = 3.80 \, \text{mol}\][/tex]
2. Oxygen [tex](O\(_2\))[/tex]:
[tex]\[\text{Molar mass of O}_2 = 32.00 \, \text{g/mol}\][/tex]
[tex]\[n_{\text{O}_2} = \frac{30.6 \, \text{g}}{32.00 \, \text{g/mol}} = 0.956 \, \text{mol}\][/tex]
Now, calculate the partial pressure of each gas using the ideal gas law:
1. Partial pressure of Helium:
[tex]\[P_{\text{He}} = \frac{n_{\text{He}}RT}{V}\][/tex]
[tex]\[P_{\text{He}} = \frac{3.80 \, \text{mol} \times 0.0821 \, \text{L} \cdot \text{atm} \cdot \text{mol}^{-1} \cdot \text{K}^{-1} \times 295.15 \, \text{K}}{5.00 \, \text{L}}\][/tex]
[tex]\[P_{\text{He}} = \frac{91.99}{5.00} = 18.40 \, \text{atm}\][/tex]
2. Partial pressure of Oxygen:
[tex]\[P_{\text{O}_2} = \frac{n_{\text{O}_2}RT}{V}\][/tex]
[tex]\[P_{\text{O}_2} = \frac{0.956 \, \text{mol} \times 0.0821 \, \text{L} \cdot \text{atm} \cdot \text{mol}^{-1} \cdot \text{K}^{-1} \times 295.15 \, \text{K}}{5.00 \, \text{L}}\][/tex]
[tex]\[P_{\text{O}_2} = \frac{23.14}{5.00} = 4.63 \, \text{atm}\][/tex]
Finally, the total pressure in the tank is the sum of the partial pressures:
[tex]\[P_{\text{total}} = P_{\text{He}} + P_{\text{O}_2}\][/tex]
[tex]\( P_{\text{total}} = 23.03 \, \text{atm} \)[/tex].
Consider the following cyclic process carried out in two steps on a gas. Step 1: 50. J of heat is added to the gas, and 20. J of expansion work is performed. Step 2: 62 J of heat is removed from the gas as the gas is compressed back to the initial state. Calculate the work for the gas compression in Step 2.
Answer:
the work for the gas compression in step 2 = 32 J
Explanation:
Given that:
A system usually comes back to initial state after 2 steps;
That implies :
ΔE₁ + ΔE₂ = 0
When heat is added to a given system , q tends to be positive
q is also negative when the heat is removed from the system
The work (W) when expansion occurs is said to be negative and positive when compression occurs.
∴ ΔE₁ = q₁ + W₁
ΔE₁ = 50 J + (-20 J)
ΔE₁ = 30 J
ΔE₂ = q₂ + W₂
ΔE₂ = -62 J + W₂
ΔE₁ + ΔE₂ = 0
30 J -62 J + W₂ = 0
W₂ = - 30 J + 62 J
W₂ = 32 J
Thus, the work for the gas compression in step 2 = 32 J
Answer:
The work for the gas compression is 32 J
Explanation:
Step 1: Data given
50 J of heat is added to the gas
20 J of expansion work
62 J of heat is removed from the gas as the gas is compressed back to the initial state
Step 2:
ΔE = q + w
⇒with q = 50 J of heat
⇒with w = 20 J of expansion work
⇒ expansion work = since there is work done by the gas: w is negative
ΔE = q + w
ΔE = 50 J - 20 J
ΔE = 30J
Step 3: Calculate the work for the gas compression
ΔE = -30 J = -62 J + w
⇒62 J of heat is removed from the gas as the gas is compressed back to the initial state. Compressed gas means work done by the surroundings => w is positive
⇒To go back to the initial state, we need 30 J
ΔE = -23 J
w = -30 J + 62 J = 32 J
The work for the gas compression is 32 J
Immediately after the golf ball is hit by the putter, the ball has 12 joules of mechanical energy. Seconds later, after the ball has rolled several meters through the grass, its mechanical energy has dropped to 4 joules due to friction with the grass and air.
The amount of mechanical energy lost by the golf ball is _______ the amount of heat energy gained by the ball, grass, and air molecules due to friction.
A.
equal to
B.
less than
C.
greater than
D.
unrelated to
Answer:A equal to
Explanation:
Final answer:
The mechanical energy lost by the golf ball is equal to the heat energy gained by the ball, grass, and air due to the law of conservation of energy.
Explanation:
The amount of mechanical energy lost by the golf ball is equal to the amount of heat energy gained by the ball, grass, and air molecules due to friction. According to the law of conservation of energy, energy cannot be created or destroyed, only transferred from one form to another. In this situation, the 12 joules of mechanical energy initially present in the golf ball is reduced to 4 joules after some time. The difference, which is 8 joules, is the amount of energy that has been transformed into heat due to the forces of friction acting on the ball by the grass and air.
Calculate the Kelvin temperature to which 10.0 L of a gas at 27 °C would have to be heated to change the volume to 12.0 L. Units of Kelvin are assumed here for the answer you enter so just put the number value.
360.18 K is the Kelvin temperature to which 10.0 L of a gas at 27 °C would have to be heated to change the volume to 12.0 L.
Explanation:
Data given:
Initial volume of the gas, V1 = 10 litres
Initial temperature of the gas, T1 = 27° C or 273.15+27 = 300.15 K
Final volume of the gas obtained, V2 = 12 Litres
final temperature to obtain the above volume, T2 =?
temperature value in Kelvin
Applying Charles' Law to the data given,
[tex]\frac{V1}{T1} =\frac{V2}{T2}[/tex]
rearranging the equation to get T2,
T2 = [tex]\frac{V2T1}{V1}[/tex]
Putting the values in the equation:
T2 =[tex]\frac{ 12 X 300.15}{10}[/tex]
T2 = 360.18 K
The gas will be heated at the temperature of 360.18 K to get its volume changed to 12 litres.
According to the question,
Volume,
[tex]V_1 = 10.0 \ L[/tex][tex]V_2 = 12.0 \ L[/tex]Temperature,
[tex]T_1 = 300 \ K[/tex][tex]T_2 = \ ?[/tex]By using the relation, we get
→ [tex]PV= nRT[/tex]
then,
→ [tex]\frac{V_1}{V_2} = \frac{T_1}{T_2}[/tex]
→ [tex]T_2= \frac{T_1\times V_2}{V_1}[/tex]
By substituting the values,
[tex]= \frac{300\times 12.0}{10}[/tex]
[tex]= 360 \ K[/tex]
Thus the above answer is correct.
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The Environmental Protection Agency and health officials nationwide are concerned about the levels of radon gas in homes. The half-life of the radon-222 isotope is 3.8 days. If a sample of gas taken from a basement contains 2.1 µg of radon-222, how much radon will remain in the sample after 4.94 days? Answer in units of µg.
Answer: The amount left after 4.94 days is [tex]0.875\mu g[/tex]
Explanation:
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) for completion of half life:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]
[tex]k=\frac{0.693}{3.8}=0.18days^{-1}[/tex]
b) to calculate amount left after 4.94 days
[tex]t=\frac{2.303}{0.18}\log\frac{2.1\mu g}{a-x}[/tex]
[tex]4.94=\frac{2.303}{0.18}\log\frac{2.1\mu g}{a-x}[/tex]
[tex]\log\frac{2.1\mu g}{a-x}=0.39[/tex]
[tex]\frac{2.1\mu g}{a-x}=2.4[/tex]
[tex]{a-x}=0.875\mu g[/tex]
The amount left after 4.94 days is [tex]0.875\mu g[/tex]
Which structures are common to both prokaryotic and eukaryotic cells? Check all that apply.
vacuole
cell membrane
Golgi body
ribosome
cytoplasm
endoplasmic reticulum
Answer:
cell membrane
ribosome
cytoplasm
Explanation:
Just believe in me
The structures that are common to both prokaryotic and eukaryotic cells are:
Cell membrane is the wall that cells have, allowing them to remain independent from the external environment.Ribosome are the macromolecules responsible for the synthesis or translation of amino acids.Cytoplasm is the region of a cell that is found between the nucleus and the plasma membrane, gives support, shape and movement to the cell and stores molecules.The main parts of all cells in both prokaryotes and eukaryotes are the cell or plasma membrane, and the compartment that it encloses, called the cytoplasm.
The cell membrane is characterized by being semi-permeable, dynamic and with the ability to be modified.
The cytoplasm fulfills three functions which are:
Structural it is not only the one that shapes the cell but also the key to its movements.The nutritive because it has substances that are later transformed into energy.Storage it keeps reserve substances.Ribosomes are responsible for intervening in protein biosynthesis in the cytoplasm.
Therefore, we can conclude that the structures that are common to both prokaryotic and eukaryotic cells are cell membrane, ribosome
and cytoplasm
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a) What is the maximum number of grams of nickel bromide that can be produced from the reaction of 67.8 g of nickel with 37.3 g of bromine?
b) Which reactant is in excess and what mass of this reactant is left over?
______ Ni + _______ Br2 _______ NiBr2
Answer:
The answer to your question is a) 51.07 g of NiBr₂ b) Nickel, 54 g
Explanation:
Data
mass of NiBr₂ = ?
mass if Ni = 67.8 g
mass of Br = 37.3 g
Balanced chemical reaction
Ni + Br₂ ⇒ NiBr₂
Process
1.- Find the atomic mass of the reactants and the molar mass of the product
Ni = 59 g
Br = 79.9 x 2 = 159.8 g
NiBr₂ = 59 + 159.8 = 218.8 g
2.- Find the limiting reactant
theoretical yield Ni/Br₂ = 59/159.8 = 0.369
experimental yield Ni/Br₂ = 67.8/37.3 = 1.81
The limiting reactant is Bromine because the experimental yield was lower than the theoretical yield.
3.- Calculate the mass of NiBr₂
159.8 g of Br₂ --------------- 218.8 g of NiBr₂
37.3 g of Br₂ -------------- x
x = (37.3 x 218.8) / 159.8
x = 8161.24/159.8
x = 51.07 g of NiBr₂
4.- Find the excess reactant
The excess reactant is Nickel
59 g of Ni ---------------- 159.8 g of Br₂
x ---------------- 37.3 g of Br₂
x = (37.3 x 59)/159.8
x = 2200.7/159.8
x = 13.77 g of Ni
Excess Ni = 67.8 - 13.77
= 54 g
Final answer:
The maximum number of grams of nickel bromide that can be produced is 50.911 grams. Bromine is the limiting reactant, and there will be 54.124 grams of excess nickel left over after the reaction.
Explanation:
To determine the maximum number of grams of nickel bromide (NiBr₂) that can be produced from 67.8 g of nickel (Ni) and 37.3 g of bromine (Br₂), we first need to write the balanced chemical equation: Ni + Br₂ → NiBr₂
Next, we calculate the molar mass of nickel (Ni) as approximately 58.69 g/mol and bromine (Br₂) as approximately 159.808 g/mol. Using these values, we convert the given masses of nickel and bromine to moles.
67.8 g Ni × (1 mol Ni / 58.69 g Ni) = 1.155 moles Ni
37.3 g Br₂ × (1 mol Br₂ / 159.808 g Br₂) = 0.233 moles Br₂
The balanced equation shows a 1:1 molar ratio between Ni and Br₂; therefore, the limiting reactant is the one with fewer moles. In this case, Br₂ is the limiting reactant since 0.233 moles Br₂ is less than 1.155 moles Ni. To calculate the maximum mass of NiBr₂ produced, we use the molar mass of NiBr₂ (approximately 218.498 g/mol):
0.233 moles Br₂ × (1 mol NiBr₂ / 1 mol Br₂) × (218.498 g NiBr₂ / 1 mol NiBr₂) = 50.911 grams NiBr₂
Nickel is in excess, and to find the excess mass, we calculate how much Ni is used to react with all the Br₂:
0.233 moles Br₂ × (1 mol Ni / 1 mol Br₂) × (58.69 g Ni / 1 mol Ni) = 13.676 grams Ni used
Subtracting the amount of Ni used from the original mass gives us the excess mass of Ni:
67.8 g Ni - 13.676 g Ni used = 54.124 grams Ni left over
What is the volume of a gas at 90.0°C, if it occupies 1.41 L at 170°C?
Answer:
50
Explanation:
To find the volume of the gas at 90.0°C, Charles's Law is applied after converting the temperatures to Kelvin. The new volume is found to be approximately 1.16 L.
The student asked: What is the volume of a gas at 90.0°C, if it occupies 1.41 L at 170°C? To solve this question, we will assume that the pressure and the amount of gas remain constant and apply Charles's Law, which states that the volume of a gas is directly proportional to its temperature in Kelvin. Hence, we can set up the following ratio based on Charles's Law: V₁/T₁ = V₂/T₂ , where V₁ is the initial volume, T₁ is the initial temperature, V₂ is the final volume we want to find, and T₂ is the final temperature.
First, we need to convert the temperatures from Celsius to Kelvin (where K = °C + 273.15). This gives us T₁ = 170°C + 273.15 = 443.15 K and T₂ = 90.0°C + 273.15 = 363.15 K. Now we can use Charles's Law:
V₁/T₁ = V₂/T₂
1.41 L / 443.15 K = V₂ / 363.15 K
Now, solve for V₂:
V₂ = V₁ × (T₂/T₁)
V₂ = 1.41 L × (363.15 K / 443.15 K)
V₂ ≈ 1.41 L × (0.8195)
V₂ ≈ 1.16 L
The correct answer for the volume of the gas at 90.0°C is approximately 1.16 L.
The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii.)(A) Mg²⁺ and O²⁻(B) Ba²⁺ and S²⁻(C) Na⁺ and F⁻ (D) K⁺ and Br⁻
Answer:
(A) Mg²⁺ and O²⁻
Explanation:
The pair of ions for which the energy that is required to separate the ions largest is Mg²⁺ and O²⁻.
Lattice energy is the energy released when ions combine to form the lattice structure of an ionic compound.
Lattice energy depends on the size of the both ions. Smaller ions have a larger lattice energy and a largest energy required to separate the ions.
Looking at the options, the both smallest pair of ions is Mg²⁺ and O²⁻ hence they have the highest lattice energy and largest energy to separate the ions.
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A chemical reaction was used to produce 2.54 moles of copper(II) bicarbonate, Cu(HCO3)2. What mass of copper(II) bicarbonate was produced?
The mass of copper(II) bicarbonate (Cu(HCO3)2) produced in the chemical reaction, if the yield is 2.54 moles, is approximately 563.3 grams.
Explanation:To find the mass of copper(II) bicarbonate, we need to use the molar mass of copper(II) bicarbonate, which can be found by adding the molar masses of each constituent atom. Copper(II) bicarbonate, Cu(HCO3)2, has a molar mass of 221.6 grams/mole.
Knowing we've produced 2.54 moles, we can multiply this by the molar mass:
2.54 moles * 221.6 grams/mole = 563.3 grams.
Therefore, the mass of copper(II) bicarbonate produced is approximately 563.3 grams. This calculation is based on the principle of stoichiometry, which deals with the quantifiable relationship of reactants and products in a chemical reaction.
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29. A gas has a volume of 1.75 L at -23°C and 150.0 kPa.
At what temperature would the gas occupy 1.30 L at
210.0 kPa?
The answer for the following mention bellow.
Therefore the final temperature of the gas is 260 kExplanation:
Given:
Initial pressure ([tex]P_{1}[/tex]) = 150.0 kPa
Final pressure ([tex]P_{2}[/tex]) = 210.0 kPa
Initial volume ([tex]V_{1}[/tex]) = 1.75 L
Final volume ([tex]V_{2}[/tex]) = 1.30 L
Initial temperature ([tex]T_{1}[/tex]) = -23°C = 250 k
To find:
Final temperature ([tex]T_{2}[/tex])
We know;
According to the ideal gas equation;
P × V = n × R ×T
where;
P represents the pressure of the gas
V represents the volume of the gas
n represents the no of moles of the gas
R represents the universal gas constant
T represents the temperature of the gas
We know;
[tex]\frac{P*V}{T}[/tex] = constant
[tex]\frac{P_{1} }{P_{2} }[/tex] × [tex]\frac{V_{1} }{V_{2} }[/tex] = [tex]\frac{T_{1} }{T_{2} }[/tex]
Where;
([tex]P_{1}[/tex]) represents the initial pressure of the gas
([tex]P_{2}[/tex]) represents the final pressure of the gas
([tex]V_{1}[/tex]) represents the initial volume of the gas
([tex]V_{2}[/tex]) represents the final volume of the gas
([tex]T_{1}[/tex]) represents the initial temperature of the gas
([tex]T_{2}[/tex]) represents the final temperature of the gas
So;
[tex]\frac{150 * 1.75}{210 * 1.30}[/tex] = [tex]\frac{260}{T_{2} }[/tex]
([tex]T_{2}[/tex]) =260 k
Therefore the final temperature of the gas is 260 k
Which will become completely dissociated when dissolved in water? Ammonia pyridine sulfuric acid or acetic acid
Answer:
sulfuric acid
Explanation:
Sulfuric acid is a strong electrolyte.
- Strong electrolytes dissolve completely in water.
Acetic acid and Ammonia is a weak electrolyte.
- Weak electrolytes only partially dissolve in water.
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In a presentation about measuring mass, one of your classmates states, "Two objects of the same size will always have the same mass.” Is this statement correct? Why or why not?
Two objects of the same size will not have the same mass.
Explanation:
Mass is the amount of the matter present in an object.
If the size and shape differs then the mass in that object will also differ.
For example, if we take 2 balls of the same size namely one plastic ball and other one rubber ball.
Both the balls are of same size, but the mass present in plastic ball is lesser when compared to the rubber ball.
So rubber ball has more mass than the plastic ball, and so it is concluded that two objects of the same size will not always have the same mass.
Answer:
Different objects contain different amounts of matter, even if they are the same size. Therefore, two objects of the same size can have different masses.
Explanation:
sample response on edg :)
When this element was discovered, it exhibited luster and malleability, and it reacted very vigorously with water. This element is never found as a free element in nature and always exists in a compound. To which group does this element most likely belong?
a) alkali metals
b) halogens
c) noble gases
d) transition metals
Answer:
a) alkali metals
Explanation:
The element described above definitely belonged to the alkali metals, the first group on the periodic table. They show the properties indicated in the text.
They are metals because only metals are lustrous and malleable. This eliminates the possibility of them being halogens and noble gases. Only group 1 metals reacts vigorously with water to form alkali. Alkali are aqueous solutions that are basic in nature. The reactivity of group 1 metals is due to their one extra electrons in the outer most shell. These electrons are easily and readily lost in order for such atoms to gain stability and replicate the nearest noble gases. The most reactive metal belongs to this group elements. This is why it is nearly impossible to find them occurring alone in free state. Some of the elements in this group are Li, Na, K, Rb, Cs and Fr. Transition metals have variable oxidation states and some can be found alone in nature.Which statement describes the energy changes that occur as bonds are broken and formed during a chemical reaction? 1.Energy is absorbed when bonds are both broken and formed. 2.Energy is released when bonds are both broken and formed. 3.Energy is absorbed when bonds are broken, and energy is released when bonds are formed. 4.Energy is released when bonds are broken, and energy is absorbed when bonds are formed.
The statement which describes the energy changes that occur as bonds are broken and formed during a chemical reaction is: 3. Energy is absorbed when bonds are broken, and energy is released when bonds are formed.
A chemical bond can be defined as the forces of attraction that are existing between ions, crystals, atoms or molecules and they are mainly responsible for the formation of new chemical compounds.
In Chemistry, the amount of energy that is required to break one (1) mole of a particular chemical bond is referred to as bond energy. Also, bond energy is measured in kJ/mol.
Generally, chemical bonds are broken when energy is absorbed such as in an endothermic reaction while chemical bonds are formed when energy is released such as in an exothermic reaction.
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Energy is absorbed to break chemical bonds and released when new bonds form during a chemical reaction; the overall energy change depends on the balance of these processes.
Explanation:The statement that describes the energy changes that occur as bonds are broken and formed during a chemical reaction is: "Energy is absorbed when bonds are broken, and energy is released when bonds are formed." During a chemical reaction, there is an initial investment of energy required to break the chemical bonds of reactants. This is because bonds have potential energy or "stored energy" that must be overcome. When new bonds form in the products of the reaction, this stored energy is released, usually as heat. Whether the entire chemical process is endothermic (absorbing energy) or exothermic (releasing energy) depends on the balance between the energy required to break bonds and the energy released upon forming them.