Answer:
0.158g/L.
Explanation:
MM of helium gas or He =4 g/mol
P = 0.974 atm
T = 27 °C, but we need absolute temperature.
TK = TC + 273
T = 27 + 273 = 300 K
m/V = (4 g/mol · 0.975 atm) / (0.0821 L·atm/mol·K · 300 K)
m/V = 0.975/6.1575 g/L
m/V = 0.158g/L
Answer: The density of the helium is 0.158g/L.
Question 11 of 30
During a reaction, the enthalpy of formation of an intermediate is -286
kJ/mol. During the reaction, 2 moles of the intermediate are produced. What
is the enthalpy value for this step of the reaction?
O A. -286 kJ
B. 572 kJ
OC. 286 kJ
OD. -572 kJ
By convention, the standard enthalpy of formation of all elements in their standard states are assumed to be zero. Here the enthalpy value for the intermediate formation step is -572 kJ. The correct option is D.
What is enthalpy of formation?The standard enthalpy of formation of a compound is defined as the enthalpy change accompanying the formation of one mole of the compound from its constituent elements, all the substances being in their standard states.
The symbol used to represent the standard enthalpy of formation is ΔfH⁰. The knowledge of standard enthalpies of various substances is useful for calculating the standard enthalpies of a reaction.
The overall energy difference between the reactants and products remains the same no matter how many intermediates there are in the reaction pathway.
The enthalpy value = 2 × -286 = -572 kJ
Thus the correct option is D.
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All else being equal, air volume increases when pressure decreases. Use this relationship to explain why warm air at the equator rises up through the less dense air above it.
The relation between the volume and the pressure of the gas can be given by the ideal gas equation. Warm air has more volume and low pressure that makes them rise above the equator.
What is atmospheric pressure?Pressure present and exerted by the atmospheric gases are called atmospheric pressure. The volume of the gas is in inverse relation to the pressure of the gas.
Warm air has a high volume compared to cold air. More volume results in low pressure making them rise above the dense layer of the equator region.
Therefore, the warm air rises due to a decrease in pressure.
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Find the pressure in mm HG produced by 2.35 g of carbon dioxide in a 5.00 L flask at 18 C?
Answer:
194 mm Hg or 193.8mm Hg
Explanation:
273+18=291 K
2.35g /44
=0.0534 moles
P=0.0534 mol×0.082×29 / 5L
=0.2548 atm
0.255 × 760
=193.8 mmHg
Which statement best describes what makes a base weak
The statement that describes what makes a base weak is that the base will be unable to dissociate completely in water.
What is a base?A base is any of a class of generally water-soluble compounds, having bitter taste, that turn red litmus blue, and react with acids to form salts.
Bases usually dissociate into hydroxide ions (OH-) when in an aqueous solution.
However, a base is termed weak or strong depending on it's ability to dissociate completely. A weak base does not dissociate completely into hydroxide ions when in an aqueous solution.
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A sample of hydrogen gas occupies 92 mL at 602C. If the pressure is held constant, what volume will the gas occupy when cooled to 83C?
Answer:
hydrogen gas will occupy 0.0374 liters when is cooled to 83 °C.
Explanation:
• T1 =602 °C = 875 K
• V1 =92 mL = 0.092 L
0.092L/875K= 1.05×10-⁴L/K
vf =nR/P T f= 1.05×10-⁴L/K ×356K
=0.0374 L
Why would you use a solution, such as a cabbage ph indicator, to measure the ph of household items?.
Answer:
Discussion: Red cabbage is useful as a pH indicator because the leaves contain a pigment molecule from the family of anthocyanins (shown below) which are responsible for many of the red/purple/blue colors observed in fruits and vegetables. In neutral solutions, the color observed is purple.
hope this helps:3
Based on reference table G what is the maximum number of grams of KCI(s) that will dissolve in 200 grams of water at 50•c to produce a saturated solution
About 80g of KCl will dissolve in 200g of water at 50 degrees.
What is a saturated solution?A saturated solution contains just as must solute as it can normally hold at a given temperature.
Looking at the table we can see that about 40 g of KCl dissolves in 100 g of water at 50 degrees hence about 80g of KCl will dissolve in 200g of water at 50 degrees.
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Give one example of Lewis acid
Answer:
Copper (Cu2) , Iron (Fe2+ Fe3 +) , and Hydrogen ion (H+)
Explanation:
I hope it helps u dear! ^_^
Temperature Change Curing Phase Change (5 pts)
Water boils at 100 °C. You boil a pot containing 500 g of water for 10 minutes.
What is the temperature of the water after 10 minutes of constant boiling? (Hint this question does not require any math).
Explain your answer by discussing heat and state change.
Answer:
since water boil at 100 °C .so 500gof water Will still boil at 100 °C
How many moles of water (H2O) does 10.82 x 1023 molecules represent? Round your answer to the hundredths place.
No of moles
[tex]\\ \rm\Rrightarrow \dfrac{No\:of\: molecules}{Avagadro\:no}[/tex]
[tex]\\ \rm\Rrightarrow \dfrac{10.82\times 10^{23}}{6.023\times 10^{23}}[/tex]
[tex]\\ \rm\Rrightarrow 1.80mol[/tex]
So
[tex]\boxed{\sf No\:of\: molecules=No\:of\:moles\times Avagadro\:no}[/tex]
[tex]\\ \tt{:}\longrightarrow 10.82\times 10^{23}=n\times 6.023\times 10^{23}[/tex]
[tex]\\ \tt{:}\longrightarrow n=\dfrac{10.82}{6.023}[/tex]
[tex]\\ \tt{:}\longrightarrow n=1.8mol[/tex]
Roger has determined the point of origin of a fire at a crime scene. What should he traditionally NOT collect from
this area of the crime scene to use as evidence?
When investigative officers get to a crime scene, they do not need to collect water samples.
What is a crime scene?A crime scene is a place where an offence has been committed. It is usually cordoned off to enable investigation of the crime and the collection of samples.
When investigative officers get to a crime scene, they do not need to collect water samples.
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Answer:A
Explanation:.
Calculate the AH for the reaction C₂H4 (9) + H₂ (9)→ C₂H6 (g), from the following:
a. C₂H4 (g) + 3 O₂ (g) → 2 CO₂ (g) + 2 H₂O (1)
b. 2 C₂H6 (g) + 7 O₂ (g) → 4 CO₂ (g) + 6 H₂O (1)
c. 2 H₂ (g) + O₂ (g) → 2 H₂O (1)
AH = - 1411. KJ
AH = - 3120. KJ
AH = -571.6 kJ
The AH for the reaction is -137 kJ
What is Enthalpy of Formation ?Enthalpy of formation is the energy required by reactants to convert into products . It value can be positive or negative depending on the type of reaction, Endothermic or Exothermic.
In the question 3 step reaction is given
C₂H4 (g) + 3 O₂ (g) → 2 CO₂ (g) + 2 H₂O (1) AH = - 1411. KJ
2 C₂H6 (g) + 7 O₂ (g) → 4 CO₂ (g) + 6 H₂O (1) AH = - 3120. KJ
2 H₂ (g) + O₂ (g) → 2 H₂O (1) AH = -571.6 kJ
To determine the enthalpy of formation for
C₂H4 (9) + H₂ (9)→ C₂H6 (g)
Adding reaction 1 and (1/2) 3 will give
C₂H4 (g) + 7/2 O₂ (g) + H₂ (g) ----> 2 CO₂ (g) + 3H₂O AH = -1696.8
For the second reaction
We will reverse the reaction and multiply it by 1/2
2 CO₂ (g) + 3 H₂O (1) --> C₂H6 (g) + 7/2 O₂ (g) AH = +1560
Adding the two new reactions.
C₂H4 (9) + H₂ (9)→ C₂H6 (g) AH = -137 kJ
Therefore The AH for the reaction is -137 kJ
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Calculate the equilibrium concentration of Cu2+ in a solution initially with 0.050 M Cu2+ and 1.00 M NH3.
From the calculations, the equilibrium constant of the reaction is given as 0.050
What is equilibrium constant?The term equilibrium constant refers to the number that shows the extent to which reactants are converted into products.
The equilibrium constant of this reaction can be obtained from;
K = [0.050] [1.00]^4
K = 0.050
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Which activity helps some animals maintain their body temperature?
A. Breathing in carbon dioxide
B. Making sugars
C. Rolling in mud
D. Running away from danger
Heat that flows by conduction is the transfer of thermal energy between substances in contact. What must occur for this to happen? A. The two systems must be the same temperature.
B. The two systems must not be touching each another.
C. One system must have higher kinetic energy than the other system.
D. The thermal energy of one system must be the same as the thermal energy of the other system.
Answer:
c. one must have a higher kinetic energy than the other system
Question 5 of 20:
Select the best answer for the question.
5. When considering gravity acceleration and the force of acceleration, what must be true?
O A. The direction of acceleration must be perpendicular to the direction of the force.
O B. The direction of the force and the direction of acceleration must be opposite of each other.
OC. The direction of the force and the direction of acceleration must be the same as each other.
O D. The mass of the body must be the same as the acceleration of the body.
Mark for review (Will be highlighted on the review page)
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three examples of physical chemistry from our surroundings?
Answer:
Burning of paper and log of wood.
Digestion of food.
Boiling an egg.
Explanation:
Calculate 5.1234 + 0.033÷ 1.650 and report to the correct number of significant figures.
5.1434 contains 5 significant figures and 4 decimals.
What is a significant figure?All zeros that occur between any two non-zero digits are significant. For example, 108.0097 contains seven significant digits.
Calculation:
5.1234 + 0.033÷ 1.650 = 5.1434
5.1434 contains 5 significant figures and 4 decimals. 5.1434 rounded to 4 sig figs is 5.143, to 3 sig figs is 5.14, and to 2 sig figs is 5.1.
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how to explode stuff
1 When a piece of sodium metal is dropped into water, hydrogen gas is released leaving a
solution of sodium hydroxide.
(a) Write a balanced equation for this reaction.
(b) Calculate the mass of hydrogen gas released when 43.9 g of sodium reacts.
Answer:
When sodium metal is dropped in water, hydrogen gas is evolved. Thus, the reaction is, 2Na+2H2O→H2+2NaOH. In the reaction, sodium hydroxide is formed and hydrogen gas is evolved.
Explanation:
(5 pts) Calculating Heat from Thermochemical Equations
The thermochemical equation for the combustion of methane gas is:
Calculate much heat is released when 3.5 moles of methane gas undergo a combustion reaction.
The heat that is released by the combustion of 3.5 moles of methane is 3115 kJ/mol.
What is a thermochemical equation?A thermochemical equation is a reaction equation that incorporates the amount of heat lost/gained.
In this case, the reaction equation is; CH4 + O2 ----->CO2 + 2H2O dH = -890 kJ/mol
If 1 mole of methane releases 890 kJ/mol
3.5 moles of methane will release 3.5 moles * 890 kJ/mol/1 mole
= 3115 kJ/mol
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What quantity in moles of CH₂OH are there in 150.0 mL of 0.210 M
CH₂OH?
Answer:
0.0315 moles CH₂OH
Explanation:
You can find the amount of moles using the molarity equation. This equation looks like this:
Molarity (M) = moles / volume (L)
Once you convert mL to L (by dividing by 1,000), you can plug the molarity and volume into the equation and isolate to find moles. The final answer should have 3 sig figs because the given value with the lowest amount of sig figs (0.210 M) has this amount.
150.0 mL / 1,000 = 0.1500 L
Molarity = moles / volume
0.210 M = moles / 0.1500 L
(0.210 M x 0.1500 L) = moles
0.0315 = moles
balence this equation pleaseeee
with some steps and explanations
H₂O + 0₂ → H₂O2
thanks in advance
Answer:
2H2O+O2-2H2O2
Explanation:
TO BALANCE equation both side should be equal
noltoupe sonblod
Example: Ksp for cadmium carbonate is 1.8 * 10-14, calculate
the equilibrium solubility of cadmium carbonate in a solution at
constant pH of 11?
For H₂CO3
1- Ka = 4.45 * 10-7
2-ka =4.7*10-11
The equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is 1.65 x 10⁻⁵ mol/dm³.
Equilibrium solubility of the compound
The equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is calculated as follows;
H₂CO3 ⇄ 2H⁺ + CO₃²⁻
x : 2x x
ksp = (2x)²x
ksp = 4x³
(1.8 x 10⁻¹⁴) = 4x³
(1.8 x 10⁻¹⁴) /4 = x³
4.5 x 10⁻¹⁵ = x³
x = (4.5 x 10⁻¹⁵)^¹/₃
x = 1.65 x 10⁻⁵ mol/dm³
Thus, the equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is 1.65 x 10⁻⁵ mol/dm³.
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The equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is 1.65 x 10⁻⁵ mol/dm³.
What is solubility?Solubility is defined as the maximum amount of a substance that will dissolve in a given amount of solvent at a specified temperature.
The equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is calculated as follows;
H₂CO3 ⇄ 2H⁺ + CO₃²⁻
x : 2x x
ksp = (2x)²x
ksp = 4x³
(1.8 x 10⁻¹⁴) = 4x³
(1.8 x 10⁻¹⁴) /4 = x³
4.5 x 10⁻¹⁵ = x³
x = [tex](4.5 X 10^{-15})^{\frac{1}{3} }[/tex]
x = 1.65 x 10⁻⁵ mol/dm³
Thus, the equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is 1.65 x 10⁻⁵ mol/dm³.
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If you dissolve 25.0 g of NaNO3 (Mm = 85.0 g) in 155 mL of water, what is the molarity of the solution? (Report your answer to two places past the decimal point)
Answer:
1.90 M
Explanation:
To find the molarity of the solution, you need to use the molarity equation. This formula looks like this:
Molarity (M) = moles / volume (L)
To use this equation, you need to perform some conversions. You should (1) convert mL to L (by dividing by 1,000), then (2) convert grams NaNO₃ to moles (via molar mass), then (3) plug moles and volume into the molarity equation.
155 mL / 1,000 = 0.155 L
25.0 g NaNO₃ 1 mole
--------------------- x ----------------- = 0.294 moles NaNO₃
85.0 g
Molarity = moles / volume
Molarity = 0.294 moles / 0.155 L
Molarity = 1.8975....
Molarity = 1.90 M
what is the mass of 3.55×10−2 mol Ba
Answer:
4.87 g
Explanation:
The formula between the number of moles, mass and Mr can be used to find the mass of barium.
Number of moles = mass ÷ Mr
So, mass = number of moles × Mr
Mr of Ba = 137.3
∴ Mass = (3.55 × 10⁻²) × 137.3 = 4.87 g
Light refracts because:
000
it is reflected at a focal point.
it changes speed.
its frequency does not match the object it is striking.
All of the choices are correct.
Unit 1
Refraction is caused due to the change in speed of light when it enters from one medium to another. Hence, option B is correct.
What is refraction?Refraction happens when light changes direction, or bends when it moves from one material to another.
The cause of the refraction of light is that light travels at different speeds in different media.
This change in the speed of light when it moves from one medium to another causes it to bend.
Thus, refraction is caused due to the change in speed of light when it enters from one medium to another. Hence, option B is correct.
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How many grams do 6.534e+24 molecules of phosphoric acid weigh?
Answer:
1,063 grams H₃PO₄
Explanation:
To find the mass of phosphoric acid (H₃PO₄), you should (1) convert molecules to moles (via Avogadro's number) and then (2) convert moles to grams (via molar mass from periodic table).
Molar Mass (H₃PO₄): 3(1.008 g/mol) + 30.974 g/mol + 4(15.998 g/mol)
Molar Mas (H₃PO₄): 97.99 g/mol
6.534 x 10²⁴ molecules H₃PO₄ 1 mole 97.99 g
--------------------------------------------- x ------------------------------------- x --------------
6.022 x 10²³ molecules 1 mole
= 1,063 grams H₃PO₄
describe a weather station that will be used to collect weather data it should collect data that are needed to make forecasts. explain what data are needed how the station would be powered and any other relevant information . Then sketch it out
(please draw a sketch arigato)
The weather station is a place which contain instrument that collect data of atmospheric pressure, wind, humidity, etc to forecast weather. The weather station is powered by solar power.
What is a weather station?A weather station is a place that measure atmospheric conditions, on the basis of temp., pressure, wind speed, etc conditions.
They can be based either in land or sea. They are necessary to forecast any disaster, so we can prepare for the disaster.
Thus, the weather station is a place which contain instrument that collect data of atmospheric pressure, wind, humidity, etc to forecast weather. The weather station is powered by solar power.
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show the step by step hybridization of hydroxonium ion H3O, draw the diagram showing the geometry and the bond angle
The central oxygen atom is a state of sp3 hybridization having only one available lone pair.
What is hybridization?The term hybridization refers to the mixing of two or more atomic orbitals to yield hybrid orbitals that are suitable for bonding.
Looking at the ion H3O^+, we can see that the central oxygen atom is a state of sp3 hybridization having only one available lone pair. The image of the ion is shown here.
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