(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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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
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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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:
Give one example of Lewis acid
Answer:
Copper (Cu2) , Iron (Fe2+ Fe3 +) , and Hydrogen ion (H+)
Explanation:
I hope it helps u dear! ^_^
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
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:.
(a) Why does one side of the brain is affected when other side is damaged?
Answer:
Because the brain is connected.
Explanation:
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
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.
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In an experiment, the molar mass of the compound was determined to be 118.084 g/mol. What is the molecular formula of the compound?
The molecular formula of the compound is C₄H₈O₄.
What is the molecular formula of a compound?The molecular formula is the exact whole number ratio of the compound's elements. The empirical formula, as well as the molecular mass, are combined to generate the molecular formula.
Let's assume that the compound contains:
40.6 grams of carbon, 5.1 grams of hydrogen, and 54.2 grams of oxygen.The empirical formula of the compound is:
C H O
40.6/12 5.1/1 54.2/16
3.38 5.1 3.38
Divide by the smallest value
3.38/3.38 5.1/3.38 3.38/3.38
1 1.5≅ 2 1
= C₁H₂O₁
The empirical formula weight = (1 × 12) + (2 × 1) + (1 × 16)
The empirical formula weight = 30 g/mol
Molecular formula = (118.084 g/mol)/30 g/mol
Molecular formula = 3.94 ≅ 4
Therefore, the molecular formula for the compound is C₄H₈O₄.
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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
40 points!!!!!!!!!!!!!!!!!!!!!
Answer:
4.041 moles C₂H₆
Explanation:
To convert from grams to moles, you first need to determine the molar mass of C₂H₆. The molar mass is the combination of the atomic masses times the quantity of each element present in the molecule. The atomic masses usually be found on the periodic table. They represent how much the element weighs per one mole.
Carbon (C) Atomic Mass: 12.01 g/mol
Hydrogen (H) Atomic Mass: 1.008 g/mol
Molar Mass (C₂H₆): 2(12.01 g/mol) + 6(1.008 g/mol)
Molar Mass (C₂H₆): 30.068 g/mol
Now that you have the molar mass, you can multiply this ratio to the given value. Keep in mind that in order to go from grams to moles, the numerical value should be place in the denominator of the molar mass ratio. This allows for the cancellation of the unit 'grams'. The final answer should have 4 significant figures because the given value also has 4 sig figs.
121.5 grams C₂H₆ 1 mole
-------------------------- x ------------------------ = 4.041 moles C₂H₆
30.068 grams
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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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
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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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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Based on the periodic table, which of the following groups of elements should have very different chemical properties?
OA. lithium (Li), sodium (Na), potassium (K)
OB. beryllium (Be), magnesium (Mg), calcium (Ca)
OC. helium (He), neon (Ne), argon (Ar)
OD.
potassium (K), aluminum (Al), neon (Ne)
Answer:
Explanation:
Comment
A: is in group 1. The properties are quite similar
B: the choices for answer B are in column or group 2. They too will have similar properties.
C: the choices there are in group 18. They do have similar properties.
The answer is D.
Potassium group 1aluminum group 3neon group 18Note: group means the same thing as column. They are vertical.
What is the mass of 15.0 ml of a liquid that has a density of 0.694 g/cm³?
Answer:
10.41 g
Explanation:
ml and cm^3 are generally interchangeable
15 cm^3 * . 694 g/cm^3 = 10.41 g
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
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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Substrate: N-benzoyl-L-tyrosine ethyl ester (BTEE) 0.001M
Buffer:0.1M tris-HCl, pH 7.8, containing 0.1M CaCl₂.
Enzyme:1mg/ml chymotrypsin A in 0.001M HCI.
N.B. The enzyme provided is a stock solution which should be diluted 50-fold with
0.001M HCl immediately before use.
How do I do this fold dilution calculation ?
Based on the dilution formula, 0.1 mL of the stock solution of the enzyme is required to prepare a 50-fold diluted enzyme in 0.01 M HCl.
How can 50-fold dilution of the enzyme be done?The 50-fold dilution of the stock enzyme solution can be done by using the dilution formula to determine the given volume of the stock solution required.
The dilution formula is given below:
C1V1 = C2V2where:
C1 = Initial concentration of enzymeC2 = Final concentration of enzymeV1 = Initial volumeV2 = Final volumeFrom the given data for the enzyme dilution;
C1 = 1
C2 = 1/50 = 0.02
V1 = x
V2 = 5 ml
Making V1 subject of formula in the dilution formula:
V1 = C2V2/C1
V1 = 0.02 * 5/1 = 0.1 mL
Therefore, 0.1 mL of the stock solution of the enzyme is required to prepare a 50-fold diluted enzyme in 0.01 M HCl.
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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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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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In an experiment, the molar mass of the compound was determined to be 118.084 g/mol. What is the molecular formula of the compound?
Answer:
need more info
Explanation:
i think so we need more info
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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three examples of physical chemistry from our surroundings?
Answer:
Burning of paper and log of wood.
Digestion of food.
Boiling an egg.
Explanation:
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