Answer:
[tex]\boxed{\text{11.8 kJ}}[/tex]
Explanation:
The formula for the heat released is
q = mCΔT
Data:
m = 28.9 g
C = 0.385 J·°C⁻¹g⁻¹
T₁ = 1083 °C
T₂ = 25.0 °C
Calculations:
(a)Temperature change
ΔT = T₂ - T₁ = 25.0 - 1083 = -1058 °C
(b) Heat released
q = 28.9 × 0.385 × (-1058) = -11 800 J = -11.8 kJ
The negative sign shows that energy is released, so the copper has released [tex]\boxed{\textbf{11.8 kJ}}[/tex] of energy.
The energy released when a 28.9 gram piece of copper cools from 1083 °C to 25.0 °C is 11771.837 J.
The question asks to calculate the energy released when a 28.9 gram piece of copper is cooled from its melting point of 1083 °C to 25.0 °C. The specific heat of copper is given as 0.385 J/g°C. To find the energy released, we can use the formula: Energy (Q) = mass (m) × specific heat (c) × change in temperature (ΔT).
In this case, ΔT (change in temperature) = final temperature - initial temperature = 25.0 °C - 1083 °C = -1058 °C (since we are cooling down, this is a negative value, indicating heat loss). Thus, the calculation becomes Q = 28.9 g × 0.385 J/g°C × (-1058 °C).
Q = 28.9 × 0.385 × (-1058) = -11771.837 joules
The energy released by the copper as it cools down is 11771.837 (since energy release is typically considered positive, we take the absolute value).
Name two things in the lab that are for safety
Answer:
Safety goggles and chemical fume hoods
Explanation:
Which of the following statements is true for real gases? Choose all that apply. As attractive forces between molecules increase, deviations from ideal behavior become more apparent at relatively low temperatures. Attractive forces between molecules cause an increase in pressure compared to the ideal gas. As attractive forces between molecules increase, deviations from ideal behavior become more apparent at relatively high temperatures. Attractive forces between molecules cause a decrease in pressure compared to the ideal gas.
Answer:
Explanation:
Attractive forces between the gase molecules become significant at lower temperatures
Reason for that is when the temperature of the molecules decrease .the kinetic energy also decreases .at a certain low temperature the gases change into the liquid state . Therefore the attractive forces between these gas molecules become very significant near liquefying temperature . that's why they deviate from their original behavior at low temperature
Real gases deviate from ideal gas behavior primarily due to intermolecular attractions and the volumes of the gas molecules. The effects of these factors are more pronounced at high pressures and low temperatures.
Explanation:The behavior of real gases deviates from ideal gas behavior due to intermolecular attractions and the finite volume of gas molecules. Attractive forces between molecules have the effect of pulling them closer together, which decreases the pressure or volume. This phenomenon is more pronounced at low temperatures as the lower kinetic energy (KE) at cold temperatures can't overcome these attractions as efficiently.
On the contrary, as the pressure increases the volume of the gas molecules themselves becomes appreciable relative to the total volume occupied by the gas. Therefore, real gases behave more like ideal gases at relatively low pressures and high temperatures, and significant deviations occur at high pressures and low temperatures.
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How much heat is given off when 64 g liquid methanol at its freezing point changes to solid methanol?
Answer:
= 6.32 Joules
Explanation:
The heat given off by a substance while changing from liquid state to solid state without change in temperature is given by the formula;
Q = n×Lf
where, Q is the heat quantity, n is the number of moles and Lf is the molar heat of fusion. The methanol HF is 3.16 kJ/mol.
The number of moles = 64 g/32 g/mol
= 2 moles
Therefore;
Heat = 2 moles × 3.16 kJ/mol
= 6.32 Joules
Answer:
6.32 kJ
Explanation:
took the test
If a tree dies and the trunk remains undisturbed for 13,750 years, what percentage of the original 14c is still present? (the half-life of 14c is 5730 years.)
Answer:
18.94%.
Explanation:
The decay of carbon-14 is a first order reaction.The rate constant of the reaction (k) in a first order reaction = ln (2)/half-life = 0.693/(5730 year) = 1.21 x 10⁻⁴ year⁻¹.The integration law of a first order reaction is:kt = ln [A₀]/[A]
k is the rate constant = 1.21 x 10⁻⁴ year⁻¹.
t is the time = 13,750 years.
[A₀] is the initial percentage of carbon-14 = 100.0 %.
[A] is the remaining percentage of carbon-14 = ??? %.
∵ kt = ln [Ao]/[A]
∴ (1.21 x 10⁻⁴ year⁻¹)(13,750 years) = ln (100.0%)/[A]
1.664 = ln (100.0%)/[A]
Taking exponential for both sides:
5.279 = (100.0%)/[A]
∴ [A] = (100.0%)/5.279 = 18.94%.
If a tree dies and the trunk remains undisturbed for 13,750 years, 18.94% of the original C-14 will still be present.
What is radioactive decay?Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation.
C-14 decays with a half-life (th) of 5730 years. We can calculate the rate constant (k) using the following expression.
k = ln2 / th = ln2 / 5730 y = 1.210 × 10⁻⁴ y⁻¹
The decay follows first-order kinetics. We can calculate the fraction of the original C-14 after 13,759 years using the following expression.
[tex][C]/[C]_0 = e^{-k.t} \\[C]/[C]_0 = e^{-(1.210.10^{-4}y^{-1} ).(13,750y)} = 0.1894 = 18.94 \%[/tex]
where,
[C] is the amount of C after a time t.[C]₀ is the original amount of C.If a tree dies and the trunk remains undisturbed for 13,750 years, 18.94% of the original C-14 will still be present.
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How many moles of compound are there in the following?
a. 6.60 g (NH4)2SO4
b. . 4.5 kg Ca(OH)2
a) (NH4)2SO4 --- 1 mole of it contains 2 moles of N, 8 moles of H, 1 mole of S, and 4 moles of O.
MM = (2 moles N x 14.0 g/mole) + (8 moles H x 1.01 g/mole) + (1 mole S x 32.1 g/mole) + (4 moles O x 16.0 g/mole) = 132 g/mole.
6.60 g (NH4)2SO4 x (1 mole (NH4)2SO4 / 132 g (NH4)2SO4) = 0.0500 moles (NH4)2SO4
b) The molar mass for Ca(OH)2 = 74.0 g/mole, calculated like (NH4)2SO4 above.
4.5 kg Ca(OH)2 x (1000 g / 1 kg) x (1 mole Ca(OH)2 / 74.0 g Ca(OH)2) = 60.8 moles Ca(OH)2
The number of mole in the compounds are:
A. 6.60 g of (NH₄)₂SO₄ contains 0.05 mole.
B. 4.5 kg Ca(OH)₂ contains 60.81 moles
The mole of a substance is related to its mass and molar mass according to the equation:
[tex]Mole = \frac{mass}{molar mass }[/tex]
With the above formula, we can obtain the answer to the questions given above. This is illustrated below:
A. Determination of the number of mole in 6.60 g of (NH₄)₂SO₄
Molar mass of (NH₄)₂SO₄ = 2[14 + (4×1)] + 32 + (4×16)
= 2[14 + 4] + 32 + 64
= 2[18] + 32 + 64
= 36 + 32 + 64
= 132 g/mol
Mass of NH₄)₂SO₄ = 6.60 g
Mole of NH₄)₂SO₄ =?[tex]Mole = \frac{mass}{molar mass }[/tex]
Mole of NH₄)₂SO₄ = [tex]\frac{6.6}{132}\\\\\\[/tex]
Mole of NH₄)₂SO₄ = 0.05 moleThus, 6.60 g of (NH₄)₂SO₄ contains 0.05 mole.
B. Determination of the number of mole in 4.5 kg Ca(OH)₂
Molar mass of Ca(OH)₂ = 40 + 2(16 + 1)
= 40 + 2(17)
= 40 + 34
= 74 g/mol
Mass of Ca(OH)₂ = 4.5 kg
= 4.5 × 1000
= 4500 g
Mole of Ca(OH)₂ =?
[tex]Mole = \frac{mass}{molar mass }[/tex]
Mole of Ca(OH)₂ = [tex]\frac{4500}{74}\\\\\\[/tex]
Mole of Ca(OH)₂ = 60.81 molesThus, 4.5 kg Ca(OH)₂ contains 60.81 moles
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How much energy is lost during an average chemical reaction?
In a reaction, there is no energy lost or created because of the law of conversion of energy. The energy is just transformed from one form to others.
What is a chemical reaction?A chemical reaction is a reaction in which the reactant are combined to form products.
In a chemical reaction, energy does not lose, it is just transformed into another form.
Thus, In a reaction, there is no energy lost or created because of the law of conversion of energy. The energy is just transformed from one form to others.
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What properties must a solid have to undergo sublimation
Answer:
Sublimation occurs in solids with vapor pressures that exceed atmospheric pressure at or near room temperature.
Explanation:
For a solid to undergo sublimation, it must have relatively low intermolecular forces on the surface allowing it to transition directly from solid to gas with the addition of energy. The heat of sublimation (AHsub) is key in understanding this process, which involves the sum of the heat of fusion and vaporization.
A solid must have certain properties to undergo sublimation. Sublimation is the direct conversion of a solid to a gas without passing through the liquid phase. To sublimate, the solid should have sufficient intermolecular forces on the surface that can be overcome relatively easily with the addition of energy, such as heat. This is why substances with higher vapor pressures near room temperature can often undergo sublimation.
The amount of energy required for a solid to sublimate is indicated by the heat of sublimation (AHsub), which is the sum of the heat of fusion (AHfus) and the heat of vaporization (AHvap). This is an application of Hess's law and signifies the total amount of energy needed to change the phase from solid to gas. The equation Q = mLs is used to calculate the energy involved in the process, where Ls represents the heat of sublimation.
Common examples of substances that can sublimate include dry ice (CO2), iodine, naphthalene, and 1,4-dichlorobenzene. Substances that sublimate have unique uses, such as dry ice being a good refrigerant, because it cools through the endothermic sublimation process without leaving a liquid residue as it transitions to gas.
When is balance achieved between the forward and reverse reactions?
Answer:
Explanation:
Balance is achieved when a reaction is in equilibrium.
At equilibrium, the rate of forward reaction is equal to the rate of backward or reverse process.
For the reaction CH4 + 2O2 → CO2 + 2H2O, how many grams of water are produced from thecombustion of 6.35 moles of methane?
Answer:
228.6 g of H₂O
Explanation:
the balanced equation for the combustion of methane is as follows
CH₄ + 2O₂ ---> CO₂ + 2H₂O
molar ratio of CH₄ to H₂O is 1:2
when 1 mol of CH₄ reacts with excess O₂, 2 mol of H₂O is formed
therefore when 6.35 mol of CH₄ reacts - 2 x 6.35 mol = 12.7 mol of H₂O is formed
therefore mass of H₂O formed is - 12.7 mol x 18 g/mol = 228.6 g of H₂O is formed
Final answer:
Using the stoichiometry of the balanced chemical equation CH4 + 2O2 → CO2 + 2H2O, 6.35 moles of methane produce 12.7 moles of water, which is equal to 228.854 grams of water.
Explanation:
To find out how many grams of water (H₂O) are produced from the combustion of 6.35 moles of methane (CH₄), we need to use the stoichiometry of the balanced chemical equation, which is CH₄ + 2O₂ → CO₂ + 2H₂O.
According to the equation, each mole of methane produces 2 moles of water. Therefore, 6.35 moles of methane will produce 6.35 * 2 = 12.7 moles of water. The molar mass of water is 18.02 g/mol, so the total mass of water produced is 12.7 moles * 18.02 g/mol = 228.854 g of H₂O.
Consider this reaction:
Which statement is most likely true about HBr?
It turns blue litmus red.
It reacts with carbon dioxide to form a carbonate.
It feels slippery.
Answer:
It turns clear phenolphthalein pink.
answer above is for second answer
Explanation:
The statement that is most likely true about HBr is It turns blue litmus red
Properties of an acidFrom the question, we are to determine which statement is most likely true about HBr
HBr is Hydrobromic acid. Since it HBr is an acid, it must have the properties of an acid
Some of the properties of an acid are
Acids have sour taste. Acids turn blue litmus red.Acids react with active metals to yield hydrogen gas.Hence, the statement that is most likely true about HBr is It turns blue litmus red
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From the data below, calculate the total heat (in j) needed to convert 0.782 mol of gaseous ethanol at 300.0°c and 1 atm to liquid ethanol at 25.0°c and 1 atm
Answer:
You must remove [tex]\text{50.6 kJ}[/tex] .
Explanation:
There are three heat transfers in this process:
Total heat = cool the vapour + condense the vapour + cool the liquid
q = q₁ + q₂ + q₃
q = nC₁ΔT₁ + nΔHcond + nC₂ΔT₂
Let's calculate these heat transfers separately.
Data:
You don't give "the data below", so I will use my best estimates from the NIST Chemistry WebBook. You can later substitute your own values.
C₁ = specific heat capacity of vapour = 90 J·K⁻¹mol⁻¹
C₂ = specific heat capacity of liquid = 115 J·K⁻¹mol⁻¹
ΔHcond = -38.56 kJ·mol⁻¹
Tmax = 300 °C
b.p. = 78.4 °C
Tmin = 25.0 °C
n = 0.782 mol
Calculations:
ΔT₁ = 78.4 - 300 = -221.6 K
q₁ = 0.782 × 90 × (-221.6) = -15 600 J = -15.60 kJ
q₂ = 0.782 × (-38.56) = -30.15 kJ
ΔT = 25.0 - 78.4 = -53.4 K
q₃ = 0.782 × 115 × (-53.4) = -4802 J = 4.802 kJ
q = -15.60 - 53.4 - 4.802 = -50.6 kJ
You must remove [tex]\text{50.6 kJ}[/tex] of heat to convert the vapour to a gas.
To find the total heat needed to convert the gaseous ethanol to liquid, one must first consider the cooling of the gaseous ethanol, then the condensation of the gaseous ethanol, and lastly cooling the liquid ethanol to 25 degrees Celsius. Each step requires a specific calculation, and the final heat value is the sum of all energies calculated in these three steps, with all values converted to the same energy unit for accuracy.
Explanation:We first need to handle the cooling of the gaseous ethanol. For this, we'll use the specific heat capacity ... Given that the heat capacity (cv) of ethanol is about 75 J/mol*K (approximated because the exact value can vary), the heat loss (q1) could be calculated in this way:
q = cv * n * ΔT = 75J/mol*K * 0.782mol * (300-25)K
Subsequently, for condensation, we'll use the heat of condensation ... Assuming the heat of condensation of ethanol to be around 38.56 kJ/mol (procured from a standard table or book), we get:
q = ΔHvap * n = 38.56 kJ/mol * 0.782 mol
Lastly, we need to consider cooling the liquid ethanol to 25°C ... Therefore, knowing that the specific heat of liquid ethanol is about 112 J/mol*K:
q = c * n * ΔT = 112J/mol*K * 0.782mol * (78.37-25)K
Summing all these energies, then converting to an identical energy unit, gives you the total energy required.
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A chemist dissolves 274.mg of pure barium hydroxide in enough water to make up 50.ml of solution. calculate the ph of the solution. (the temperature of the solution is 25°c.)
Answer:
12.81.
Explanation:
Molarity (M) is defined as the no. of moles of solute dissolved in a 1.0 liter of the solution.M = (no. of moles of solute)/(Volume of the solution (L))
M = (mass/molar mass) NaCl / (Volume of the solution (L))
mass of Ba(OH)₂ = 274 mg = 0.274 g, molar mass of Ba(OH)₂ = 171.34 g/mol, Volume of water = 50.0 mL = 0.05 L.
M = (mass/molar mass) Ba(OH)₂ / (Volume of the solution (L)) = (0.274 g / 171.34 g/mol) / (0.05 L) = 0.03 M.
Ba(OH)₂ is dissociated according to:Ba(OH)₂ → Ba²⁺ + 2OH⁻,
Every 1.0 mol of Ba(OH)₂ gives 2.0 moles of OH⁻.
∴ [OH⁻] = 2(0.032 M) = 0.064 M.
∵ pOH = -log[OH⁻]
∴ pOH = -log(0.064) = 1.194.
∵ pH + pOH = 14.
∴ pH = 14 - pOH = 14 - 1.194 = 12.81.
Bill dropped in to see Sarah. How long is it appropriate for him to stay?
15 minutes
30 minutes
one hour
It will be appropriate for bill to stay for 30 minutes.
A solution of a base differs from a solution of an acid in that the solution of a base?A. is able to conduct electricity B. is able to cause an indicator color change C. has a great [H3O+] D. has a great [OH-]
Answer:
Option D. has a great [OH⁻]Explanation:
1) Both acids and bases ionize in aqueous solutions so they are able to conduct electricity.
The ions, being charged particles, when flow through the solution are charge carriers, then they conduct electricity.
So, the option A does not state a difference between a solution of a base and a solution of an acid.
2) Both acids and bases are able to cause an indicator color change.
The usufulness of the indicators is that they are able to change of color when the pH changes either from acid to basic or from basic to acid. There are different indicators because none is suitable for the whole range of pH, but the statement B is not how solutions of base and acids differ.
3) The model of Arrhenius for acids and bases states that an acid is a substance that ionizes in water releasing H⁺ ions (this is equivalent to H₃O⁺) and a base is a substance that releases OH⁻ ions in water. Then, acids have a greater concentration of H₃O⁺ (so option C is not true for a solution of a base) and bases have a greater concentraion of OH⁻, making the option D. true.
Answer:
D. Has a great [OH-]
Explanation:
Castle learning
what did Rutherford observe that surprised him?
A. most of the alpha particles shot at the gold foil bounced back.
B. most of the alpha particles shot at the gold foil went straight through the foil.
c. none of the alpha particles went through the gold foil.
D. all of the alpha particles went straight through the gold foil.
Answer:
Some of the Alpha particles shot at the gold foil bounced back.
Explanation:
Rutherford observed that most of the alpha particles shot at the gold foil went straight through the foil.
Why Rutherford was surprised?The alpha-particle scattering experiment is an important experiment that led Rutherford to give an accurate description of the distribution of positive and negative charges within the atom. Alpha particle source is placed in the lead cavity. The alpha particles emitted by the source are collimated into a narrow beam with the help of lead and slit.
The observations of Rutherford’s Alpha Scattering Experiment are: First, he observe that most of the α-particles that are bombarded towards the gold sheet pass away the foil without any deflection, and hence it shows most of the space is empty.
The correct answer is option B.
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If the pH of a solution is 5, what is its OH ion concentration?
Answer:
1.0 x 10⁻⁹ M.
Explanation:
∵ pH = - log[H⁺].
∴ 5.0 = - log[H⁺].
log[H⁺] = - 5.0.
∴ [H⁺] = 1.0 x 10⁻⁵ M.
∵ [H⁺][OH⁻] = 10⁻¹⁴.
∴ [OH⁻] = 10⁻¹⁴/[H⁺] = (10⁻¹⁴)/(1.0 x 10⁻⁵ M) = 1.0 x 10⁻⁹ M.
What is the fraction of the hydrogen atom's volume that is occupied by the nucleus? the bohr radius is 0.529×10−10m?
The radius of an electron in the third shell of the hydrogen atom, according to the Bohr model, is calculated as 4.7628 x 10⁻¹⁰ meters.
To calculate the radius of an electron in the third shell (n=3) of the hydrogen atom according to the Bohr model of the hydrogen atom, you use the formula that relates the main quantum number (n) to the radius of the electron's orbit. The radius of an orbit (rn) in the Bohr model is given by the equation rn = n2 imes ao, where ao is the Bohr radius and equals 5.292 imes 10
11 m. For the third shell, n=3, so the calculation is r3 = 32 imes 5.292 imes 10-11 m = 9 imes 5.292 imes 10-11 m.
Therefore, the radius of an electron in the third shell is r3 = 47.628 imes 10-11 m = 4.7628 imes 10-10 m. Keep in mind that while this model provides insight, it has been refined by quantum mechanics.
A 45.9 g sample of a metal is heated to 95.2°c and then placed in a calorimeter containing 120.0 g of water (c = 4.18 j/g°c) at 21.6°c. the final temperature of the water is 24.5°c. which metal was used?
Answer:
Iron
Explanation:
Heat released by the metal sample will be equivalent to the heat absorbed by water.
But heat = mass × specific heat capacity × temperature change
Thus;
Heat released by the metal;
= 45.9 g × c ×(95.2 -24.5) , where c is the specific heat capacity of the metal
= 3245.13c joules
Heat absorbed by water;
= 120 g × 4.18 J/g°C × (24.5-21.6)
= 1454.64 joules
Therefore;
3245.13c joules = 1454.64 joules
c = 1454.64/3245.13
= 0.448 J/g°C
The specific heat capacity of the metal sample is 0.448 J/g°C. The metal use is most likely, Iron.
The metal used is copper.
Explanation:The specific heat equation, q = mcΔT, can be used to determine the metal used. By plugging in the given values and solving for the metal's specific heat, we find that the closest value is to copper. Therefore, the metal used is copper.
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What is the coefficient of the acid that produces AlCl3 in the reaction mixing Al(OH)3 and HCl after the equation has been balanced?
1
3
2
4
Answer:
3.
Explanation:
Al(OH)₃ reacts with HCl to produce AlCl₃ and water according to the balanced equation:Al(OH)₃ + 3 HCl → AlCl₃ + 3H₂O,
It is clear that 1.0 mole of Al(OH)₃ reacts with 3.0 mole of HCl to produce 1.0 mole of AlCl₃ and 3.0 moles of H₂O,
So, the coefficient of HCl is 3.
For the reaction represented by the equation 2na + cl2 how many grams of sodium chloride can be produced from 500. g each of sodium and chlorine
The reaction between sodium And chlorine yields sodium chloride. Given 500 gms each of sodium and chlorine, approximately 500 g of sodium chloride can be produced.
Explanation:The reaction 2Na + Cl2 produces sodium chloride or NaCl. To calculate the amount of sodium chloride produced from 500 g of sodium and 500 g of chlorine, we first need to know the molar mass of the elements involved. The molar mass of Sodium (Na) is 23 g/mol and Chlorine (Cl2) is 71 g/mol. Now, from the balanced equation, it is clear that 2 moles of Na (46 g) react with 1 mole of Cl2 (71 g) to produce 2 moles of NaCl, whose molar mass is 58 g/mol. Hence, 117 g of Na would react completely with 500 g of Cl2 to produce 500 g of NaCl approximately, making Sodium (Na) the limiting reactant. Therefore, from 500 g of each Sodium and Chlorine, we could theoretically produce around 500 g of Sodium Chloride (NaCl).
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Final answer:
Using stoichiometry, it is determined that 500 grams of chlorine is the limiting reactant and from this amount, 824.21 grams of sodium chloride can be produced from the reaction 2 Na + Cl2.
Explanation:
To determine how many grams of sodium chloride (NaCl) can be produced from 500 grams of sodium (Na) and 500 grams of chlorine (Cl2), we need to use stoichiometry and the balanced chemical equation:
2 Na (s) + Cl2 (g) → 2 NaCl (s)
First, we should convert the mass of the reactants to moles using their molar masses (Na = 22.99 g/mol, Cl2 = 70.90 g/mol). Then, we compare the mole ratio from the balanced equation to identify the limiting reactant. The limiting reactant will determine the maximum amount of product that can be formed.
For sodium: 500 g Na × (1 mol Na / 22.99 g Na) = ~21.75 mol Na
For chlorine: 500 g Cl2 × (1 mol Cl2 / 70.90 g Cl2) = ~7.05 mol Cl2
From the balanced equation, we know that 1 mole of Cl2 reacts with 2 moles of Na. Here, Cl2 is the limiting reactant, and it will determine the number of moles of NaCl that can be formed:
7.05 mol Cl2 × (2 mol NaCl / 1 mol Cl2) = 14.1 mol NaCl
To find the mass of NaCl produced, we multiply the moles of NaCl by its molar mass (NaCl = 58.44 g/mol):
14.1 mol NaCl × (58.44 g NaCl / 1 mol NaCl) = ~824.21 g NaCl
Therefore, 824.21 grams of NaCl can be formed from 500 grams each of Na and Cl2 when using the correct stoichiometry of the reaction.
9.69×10^25 formula units of iron(III) nitrate is equal to how many moles of Fe(NO3)3?
Answer:
160.9 mol ≅ 161.0 mol.
Explanation:
It is known that every 1.0 mole of compound or element contains Avogadro's number (6.022 x 10²³) of molecules or atoms (formula units).Using cross multiplication:
1.0 mole of Fe(NO₃)₃ contains → 6.022 x 10²³ formula units.
??? mole of Fe(NO₃)₃ contains → 9.69 x 10²⁵ formula units.
∴ The no. of moles of He contains (9.69 x 10²⁵ formula units) = (1.0 mol)(9.69 x 10²⁵ formula units.)/(6.022 x 10²³ formula units) = 160.9 mol ≅ 161.0 mol.
given the equation 2Na+Cl2 →2NaCl How many moles of NaCl will be produced from 59.0 grams of Na, assuming Cl is available in excess?
I would use dimensional analysis for this problem. You would start with the given amount of Na which is 59.0g. You are trying to find the moles of NaCl.
(59.0g Na)*(1 mol Na)/(22.99 g Na)*(2 mol NaCl)/(2 mol Na)=
2.57 mol NaCl
The units will cancel out until you are left with moles of NaCl. The answer has the correct number of significant figures (3 sig figs).
Answer: 2.56 moles
Explanation:
To calculate the moles :
[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]
[tex]\text{Moles of} Na=\frac{59.0g}{23g/mol}=2.56moles[/tex]
[tex]2Na(s)+Cl(g)\rightarrow 2NaCl(s)[/tex]
Na is the limiting reagent as it limits the formation of product and chlorine is the excess reagent.
According to stoichiometry :
2 moles of Na produce = 2 moles of NaCl
Thus 2.56 moles of Na produce =[tex]\frac{2}{2}\times 2.56=2.56moles[/tex] of NaCl
Thus 2.56 moles of NaCl are produced.
Which describes the role of oxygen in photosynthesis and cellular respiration?
Oxygen is a reactant in photosynthesis and a product of cellular respiration.
Oxygen is a product of photosynthesis and a reactant in cellular respiration.
Oxygen is produced in both photosynthesis and cellular respiration.
Answer:
Oxygen is a product of photosynthesis and a reactant in cellular respiration.
Explanation:
During photosynthesis green plants manufacture their food using carbon dioxide and water in the presence of sunlight. The product of this reaction is formation of food and oxygen gas to the environment. Therefore, oxygen is given off during photosynthesis.
During cellular respiration, organisms use oxggen gas to liberate energy from food. Most times carbon dioxide is the waste product from the reaction.
Final answer:
Oxygen is produced as a byproduct of photosynthesis and consumed as a reactant in cellular respiration. These two processes are connected in the carbon cycle, recycling oxygen and carbon dioxide in Earth's atmosphere.
Explanation:
The role of oxygen in photosynthesis and cellular respiration is reciprocal. During photosynthesis, oxygen is produced as a byproduct when water molecules are split to provide electrons. This process consumes carbon dioxide and releases oxygen. On the other hand, during cellular respiration, oxygen is a reactant that works alongside glucose to produce ATP, which is the main energy currency in cells. As a result, carbon dioxide and water are generated as waste products.
Photosynthesis and cellular respiration are intimately connected in the biological carbon cycle. The oxygen released during photosynthesis is the same oxygen that is consumed during cellular respiration. This relationship sustains life on Earth by recycling oxygen and carbon dioxide in the atmosphere. Oxygen also enables cellular respiration to occur efficiently, allowing organisms to produce the ATP necessary for cellular functions.
During nuclear decay, if the atomic number decreases by one but the mass number is unchanged, the radiation emitted is
A positron
An alpha particle
A beta particle
None of these choices are correct
OPTION A.
In nuclear decay, if the atomic number decreases by one but the mass number is unchanged, the radiation emitted is a positron. This type of decay is known as positron emission.
Explanation:During nuclear decay, if the atomic number decreases by one but the mass number is unchanged, the radiation emitted is, in fact, a positron. This type of decay is called positron emission. In positron emission, a proton in the nucleus is converted into a neutron, and a positron is emitted. This process leads to a decrease in the atomic number by one unit but the mass number remains unchanged as the overall amount of nucleons (protons + neutrons) is conserved.
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During nuclear decay, if the atomic number decreases by one but the mass number is unchanged, the radiation emitted is a beta particle.
Explanation:During nuclear decay, if the atomic number decreases by one but the mass number is unchanged, the radiation emitted is a beta particle. Beta particles are high-energy electrons or positrons that are emitted during the decay of a nucleus. They have a negative charge and are smaller than alpha particles, making them capable of penetrating further through materials. This type of decay is referred to as beta decay.
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1. When describing wavelengths, frequency is the number of crests or troughs passing through a given point over a given unit of time.
True False
2. Physics is the study of matter.
True
False
The study of chemicals and bonds is called chemistry. There are different types of elements and these are metals and nonmetals.
What is wavelength?
The wavelength is the spatial period of a periodic wave.
According to the question, the answer to both questions is as follows:-
When describing wavelengths, frequency is the number of crests or troughs passing through a given point over a given unit of time is true.Physics is the study of matter is true.For more information about the matter, refer to the link:-
https://brainly.in/question/3403229
Choose the correct statements.
A. The noble gases are very unstable.
B. In the world, elements are usually in their pure form.
C. Eight electrons in the outer shell is the most stable configuration.
D. A chemical bond is a strong attractive force between atoms.
Answer:
The correct answer to your question is: C
Explanation:
A. The noble gases are very unstable. This option is wrong because noble gases are the most stable elements.
B. In the world, elements are usually in their pure form. this option is wrong because most of the elements are part of compounds.
C. Eight electrons in the outer shell is the most stable configuration. This option is correct, metals and non metals reach stability by gaining or losing electrons to reach electrons
D. A chemical bond is a strong attractive force between atoms. This option is also right, this is a correct definition of chemical bond.
A scientist prepared an aqueous solution of a 0.45 M weak acid. The pH of the solution was 2.72. What is the percentage ionization of the acid? 19% 0.42% 42% 0.19%
Answer:
0.42%
Explanation:
∵ pH = - log[H⁺].
2.72 = - log[H⁺]
∴ [H⁺] = 1.905 x 10⁻³.
∵ [H⁺] = √Ka.C
∴ [H⁺]² = Ka.C
∴ ka = [H⁺]²/C = (1.905 x 10⁻³)²/(0.45) = 8.068 x 10⁻⁶.
∵ Ka = α²C.
Where, α is the degree of dissociation.
∴ α = √(Ka/C) = √(8.065 x 10⁻⁶/0.45) = 4.234 x 10⁻³.
∴ percentage ionization of the acid = α x 100 = (4.233 x 10⁻³)(100) = 0.4233% ≅ 0.42%.
The answer is 0.42% just did it ;)
Calculate the pka of hypochlorous acid. The ph of a 0.015 m solution of hypochlorous acid has a ph of 4.64.
Answer:
pKa = 7.46Explanation:
1) Data:
a) Hypochlorous acid = HClO
b) [HClO} = 0.015
c) pH = 4.64
d) pKa = ?
2) Strategy:
With the pH calculate [H₃O⁺], then use the equilibrium equation to calculate the equilibrium constant, Ka, and finally calculate pKa from the definition.
3) Solution:
a) pH
pH = - log [H₃O⁺] 4.64 = - log [H₃O⁺] [tex][H_3O^+]= 10^{-4.64} = 2.29.10^{-5}[/tex]b) Equilibrium equation: HClO (aq) ⇄ ClO⁻ (aq) + H₃O⁺ (aq)
c) Equilibrium constant: Ka = [ClO⁻] [H₃O⁺] / [HClO]
d) From the stoichiometry: [CLO⁻] = [H₃O⁺] = 2.29 × 10 ⁻⁵ M
e) By substitution: Ka = (2.29 × 10 ⁻⁵ M)² / 0.015M = 3.50 × 10⁻⁸ M
f) By definition: pKa = - log Ka = - log (3.50 × 10 ⁻⁸) = 7.46
which of the following best describes what happens to the force of attraction if the distance between two objects increase?
1.it varies
2.it decreases
3.it increases
4.it stays the same
Answer:
3.it increases
Explanation:
Final answer:
The force of attraction decreases when the distance between two objects increases, according to the inverse-square law for forces like gravity and electrostatic forces.
Explanation:
When the distance between two objects increases, the force of attraction between them decreases. This principle is observed in both gravitational and electrostatic forces. The magnitude of the force actually decreases as the square of the distance increases. If the distance doubles, the force between the objects would decrease to one fourth of its original value. Additionally, an increase in mass for an object in uniform circular motion will result in an increase of the required centripetal force to maintain the same speed.
What element on the periodic table is named after the european capital where it was discovered in 1923?
Answer:
The element is Hafnium
Explanation:
Hi, Hafnium was discovered in 1923 by George Charles de Hevesy y Dirk Coster in Denmark. It's name was given after the capital of that country: Copenhagen which name in latin is Hafnia.