Answer:
convert 250.0 mL in Liters :250. 0 / 1000 = 0,25 LDensity = 1.240 g/LMass
Explanation:
How do the valence electrons of an atom affect chemical reactions?
Answer:
Electrons of an atom can affect chemical reactions, because electrons have a negative charge, which can introduce a form of energy.
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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Which two nuclides are isotopes of the same element
Answer:
1940K and 1939K Isotopes are two forms of the same element that have different numbers of neutrons in the nucleus. This means same symbol, and same atomic number (subscript), but different mass number (superscript).
The parent element 42 19 K decays by beta decay. Which daughter element will
form?
O A. Ca
OB. 1 Ar
O C. C
OD. K
Answer: A
Explanation:
This means that the atomic number decreases by 1 but the mass remains constant, meaning the atomic number of the new element is 20. This corresponds to calcium.
1. Related to the number of particles in a gram of
substance and to possible motions of the
particles (2 words)
Answer:
Avogadro's number or Avogardro’s constant
Explanation:
I’m pretty sure this is correct if it’s not I’m sorry lol.
A dunk tank hold 30,533 moles of water? How many grams of water are in the tank?
The mass of water in the tank, given the data from the question, is 549594 g
What is a mole?The mole of a substance is related to its mass and molar mass according to the following equation:
Moles =[tex]\frac{mass}{molar \;mass}[/tex]
How to determine the mass of water in the tank
From the question given above, the following data were obtained:
Mole of water = 30533 moles
Molar mass of water = 18 g/mol
Mass of water = ?
The mass of the water can be obtained as follow:
Mass = mole × molar mass
Mass of water = 30533 × 18
Mass of water = 549594 g
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Please help.
Which organic product is formed in the reaction shown in the diagram?
The organic product formed in the reaction shown in the image would be bromoethane.
Substitution reaction in alkanesAlkanes, such as ethane undergoes a substitution reaction with halogens such as bromine to produce haloethanes.
For example, the equation of the reaction between ethane and bromine water is as below:
[tex]C_2H_6 + Br_2 --- > C_2H_5Br + HBr[/tex]
The products formed are bromoethane and hydrobromic acid.
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How many grams of KNO3 are required to prepare 0.250 L of 0.70 M solution?
Answer:
about 3
Explanation:
just did this for the points just being honiest
20.0 g of bromic acid, HBrO3, is reacted with excess HBr.
HBrO3 (aq) + 5 HBr (aq) → 3 H2O (l) + 3 Br2 (aq)
What is the theoretical yield of Br2 for this reaction? Round your answer to the nearest gram.
After Rounding off The percentage yield is 64%
What is Percentage Yield ?It is the ratio of actual yield to theoretical yield multiplied by 100% .
It is given in the question
20.0 g of bromic acid, HBrO3, is reacted with excess HBr.
The reaction is
HBrO₃ (aq) + 5 HBr (aq) → 3 H₂O (l) + 3 Br₂ (aq)
Actual yield = 47.3 grams
Molecular weight of Bromic Acid is 128.91 gram
Moles of Bromic Acid = 20/128.91 = 0.155 mole
Mole fraction ratio of Bromic Acid to Bromine is 1 :3
Therefore for 0.155 mole of Bromic Acid 3 * 0.155 = 0.465 mole of Bromine is produced.
1 mole of Bromine = 159.8 grams of Bromine
0.465 of Bromine = 74.31 grams of Bromine
Percentage Yield = (47.3/74.31)*100 = 63.65 %
After Rounding off The percentage yield is 64% .
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Answer:
74g
Explanation:
The other person had said that the Percentage Yield = (47.3/74.31)*100 = 63.65 %
So, since to find the percent yield you have to divide the actual yield by the theoretical yield, I would assume the theoretical yield is 74.31g (74g if you round to the nearest gram)
FLAG A nurse is preparing to administer morphine 0.05 mg/kg intermittent IV bolus to a newborn who weighs 3 kg. Available is morphine 0.5 mg/mL injection. How many mL should the nurse administer? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)
The quantity of morphine, the nurse should administer is 0.3 ml.
What is morphine?Morphine is a drug which comes under the pain relieving drugs.
The quantity of morphine is 0.05 mg/kg
The weight of the baby is 3 kg.
Available morphine is 0.5 mg/mL.
0.05 x 3 = 0.15 mg
then, 0.15 mg / 0.5 = 0.3
Thus, the quantity of morphine, the nurse should administer is 0.3 ml.
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URGENT HELP NEEDED!!! SPACE
Record your observation statements from Space Academy.
When the mass of the sun is larger, Earth moves around the sun at a faster (faster, slower) pace.
When the mass of the sun is smaller, Earth moves around the sun at a slower (faster, slower) pace.
When Earth is closer to the sun, its orbit becomes faster (faster, slower).
When Earth is farther from the sun, its orbit becomes slower (faster, slower).
For each trial, record the orbit number of each planet from the sun. Be sure to indicate the number of planets in the habitable zone after each trial. Create a different configuration of planets for each trial. An example has been supplied for you.
Orbit Number
Planet One Orbit Number
Planet Two Orbit Number
Planet Three Orbit Number
Planet Four Number of planets in the habitable zone Number of planets left in successful orbit
Example: sun's mass 1x
1
3
5
6
1
2
sun's mass 1x—Trial One
1
5
2
3
1
1
sun's mass 1x—Trial Two
1
2
0
0
2
2
sun's mass 2x—Trial One
1
0
0
0
1
0
sun's mass 2x—Trial Two
1
3
2
0
4
0
sun's mass 3x—Trial One
1
2
0
0
2
0
sun's mass 3x—Trial Two
1
0
0
0
1
3
Conclusion:
Your conclusion will include a summary of the lab results and an interpretation of the results. Please answer all questions in complete sentences using your own words.
Using two to three sentences, summarize what you investigated and observed in this lab.
You completed three terra forming trials. Describe the how the sun's mass affects planets in a solar system. Use data you recorded to support your conclusions.
In this simulation, the masses of the planets were all the same. Do you think if the masses of the planets were different, it would affect the results? Why or why not?
How does this simulation demonstrate the law of universal gravitation?
It is the year 2085, and the world population has grown at an alarming rate. As a space explorer, you have been sent on a terraforming mission into space. Your mission to search for a habitable planet for humans to colonize in addition to planet Earth. You found a planet you believe would be habitable, and now need to report back your findings. Describe the new planet, and why it would be perfect for maintaining human life.
The new planet is suitable for human life because it is similar to planet earth.
Describe the new planet, and why it would be perfect for maintaining human life?
The new planet has similar atmosphere just like the earth's atmosphere. It has large amount of vegetation that can hold large amount of animals. It is suitable for growing for different crops that provide food to humans.
So we can conclude that the new planet is suitable for human life because it is similar to planet earth.
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Which type of fault would you
find at a divergent boundary?
A. normal fault - hanging wall moves down
relative to footwall
B. hanging fault - both walls hung up and do not
move
C. reverse fault - hanging wall moves up relative
to footwall
D. strike-slip fault - fault walls slide side by side
Why would someone abuse steroids?
Answer:
Because steroids can increase strength with little effort, however this is illegal to do without medical need, and it comes with many side effects.
Explanation:
a 40 g sample of water absorbs 500 calories of energy, how much did the water temp changed?
2.99 °C is the change in temperature if a 40 g sample of water absorbs 500 calories of energy.
What is specific heat capacity?The specific heat capacity is defined as the quantity of heat (J) absorbed per unit mass (kg) of the material when its temperature increases 1 K (or 1 °C), and its units are J/(kg K) or J/(kg °C).
Given data:
m = 40 g
Q = 500 J
Specific heat capacity of water = 4.18 J/g°C
Change in Temperature =?
The formula for Heat Energy is given by:
Q = mcp∆T
where: Q - Heat Energy
m - mass
cp - specific heat
∆T = change in temperature, [tex]T_2 - T_1[/tex]
Solution:
Substituting the value of m, specific heat capacity of water and Q in the formula,
500 J = (40 g)(4.18 J/g°C)(∆T)
∆T = 2.99 °C
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3) The following reaction produces chlorine molecules:
Energy + HCl (g) + CINO3 (8) Cl₂ (8) + HNO3 (8)
a) Describe 4 ways you could increase the concentration of chlorine molecules.
b) How would cooling shift the equilibrium of this reaction?
The 4 ways to increase the concentration of chlorine molecules is listed below and the reaction will go into reverse if cooled.
What is Le Châtelier’s principle ?
Le Châtelier's principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to reestablish an equilibrium.
Energy + HCl (g) + ClNO₃ ⇄ Cl₂ + HNO₃
a. So in this reaction when at equilibrium , To increase the concentration of Chlorine molecules
1. An increase in Temperature will favour the formation of Chlorine molecules.
2. Decrease in concentration of Chlorine , or partial removal of Chlorine will result the equation to go in forward direction.
3.An Increase in the concentration of HCl will favour formation of Chlorine molecules.
4.An Increase in the concentration of CINO₃ will also favour formation of Chlorine molecules.
b. The cooling would shift the reaction into backward direction as it is an endothermic reaction in forward state.
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A The weak base ionization constant (Kb) for CH3NH2 is equal to: B [CH3NH3+][OH-] [CH3NH₂] [CH3NH3 +][OH [CH3NH2][N2 O]
The weak base ionization constant (Kb) for [tex]CH_3NH_2[/tex] is equal to
[tex]Kb = [CH_3NH^{3+}] [OH^-] / [CH_3NH_2][/tex]
What is Kb?Kb is the base dissociation constant.
The expression for the equilibrium constant, Kb is simply the ratio of the concentration of the products raised to their coefficient to the concentration of the reactants raised to their coefficient.
[tex]CH_3NH_2(aq) + H_2O(l)[/tex] → [tex]CH_3NH^{3+}(aq) + OH^- (aq)[/tex]
Thus, the expression for the equilibrium constant, Kb fo the above reaction can be written as follow:
[tex]Kb = [CH_3NH^{3+}] [OH^-] / [CH_3NH_2][/tex]
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The specific heat of aluminum is approximately
0.90 J/g °C. How much heat energy would be
required to raise the temperature of a 50 g
sample of aluminum from 20 °C to 100 °C?
Answer:
3600J
Explanation:
Q = mc∆T
= 50 x 0.9 x (100 - 20)
= 3600J
The enzyme provided is a stock solution which should be diluted 50-fold with 0.001M HCl immediately before use.
Enzyme :1mg/ml chymotrypsin A in 0.001M HCl
How do I work out this calculation, if I want the 5ml of the diluted enzyme?
In order to prepare a 50-fold diluted enzyme, 0.1 mL of the stock solution of the enzyme is taken and made up to 5.0 mL with 0.001M HCl.
What is dilution?Dilution is a process whereby a solution of lower concentration is prepared from one of a higher concentration.
Dilution is done by using the dilution formula below:
C1V1 = C2V2C1; Initial concentration of enzyme = 1 mg/mL
C2; Final concentration of enzyme = 1/50 mg/ml = 0.02 mg/ml
V1; Initial volume of enzyme = y
V2; Final volume = 5.0 ml
V1 = C2V2/C1
V1 = 0.02 * 5/1 = 0.1 mL
Therefore, in order to prepare a 50-fold diluted enzyme, 0.1 mL of the stock solution of the enzyme is taken and made up to 5.0 mL with 0.001M HCl.
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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
Atoms are spherical in shape. Therefore, the Pt atoms in the cube cannot fill all the available space. If only 74.0 percent of the space inside the cube is taken up by Pt atoms, calculate the radius in picometers of a Pt atom. The mass of a single Pt atom is 3.240 × 10−22 g. [The volume of a sphere of radius r is (4/3) πr3. The volume of a cube is l3, where l is the length of a side. Avogadro's number is 6.022 × 1023.]
Answer:
Answer:
A)6.6×10^22atoms of Pt in the cube
B)1.4×10^-8m
Explanation:
(a) Calculate the number of Pt atoms in the cube.
an edge length of platinum (Pt) = 1.0 cm.
Then Volume= 1.0 cm×1.0 cm×1.0 cm=1cm^3
Then we have volume of the cube as 1cm^3
Given:
The density Pt = 21.45 g/cm3
the mass of a single Pt atom =3.240 x 10^-22 g
Then with 1atom of the platinum element, we can calculate the number of Pt atoms in the cube as
Density of pt/mass of a single Pt atom
=(21.45 /=3.240 x 10^-22)
=6.6×10^22atoms of Pt in the cube
B)Volume of cube V=4/3πr^3
V= 4/3 ×π×r^3
V= 4.19067r^3
r^3= V/4.19067
But volume is not total volume but just 74% of it, then With 74% of the space inside the cube is taken up by Pt atoms, then we need to find 74% of volume of the cube which is 1cm^3
74/100 ×1= 0.74cm^3
Then our new volume V is 0.74cm^3
r^3=0.74/4.19067×6.620 x 10^22
r^3=2.6674×10^-24
r= 3√2.6674×10^-24
r=1.4×10^-8m
What does a negative AH for a molecule mean?
A. Energy was released when the molecule was formed from its
elements.
B. Energy was added when the molecule was formed from its
elements.
C. Energy was added when the molecule changed phases.
D. Energy was released when the molecule went through a phase
change.
A negative enthalpy (ΔH)for a molecule means energy was released when the molecule went through a phase change.
What is change in enthalpy (ΔH)?The enthalpy change of a reaction is the amount of heat absorbed or released as the reaction takes place.
Also, the amount of energy required to change the phase of a material is known as the enthalpy,
A negative enthalpy entails the amount of energy released during an exothermic reaction.
Thus, a negative enthalpy (ΔH)for a molecule means energy was released when the molecule went through a phase change.
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How many protons,neutrons, and electrons does uranium 238 have
Explanation:
92 protons 92 electrons and 146 neutrons
Answer:
92 protons, 92 electrons, 146 neutrons
Explanation:
U-238 has 92 protons, 92 electrons, 146 neutrons.
The 238 is mass number talking about protons + neutrons. Uranium will always have 92 protons so the rest of the things are neutrons (146). Electrons will always equal protons if the element is neutral (no charge) and since no charge was given the numbers will match
Use the reaction and bond information to answer the question. H2 CO2 → CH2O2 Reactant bond energies: H–H is 432 kJ/mol, C=O is 799 kJ/mol Product bond energies: C–H is 413 kJ/mol, C=O is 745 kJ/mol, C–O is 358 kJ/mol, O–H is 467 kJ/mol How much energy must this system absorb before the reaction can begin?.
345678990098765435779999999999999999995699999
Convert 3.80 mol of KCI to grams?
Answer:
283 grams KCl
Explanation:
To convert form moles to grams, you need to find the molar mass of your compound. The molar mass can be calculated using the individual molar masses of each element in the compound. These values can be found on the periodic table.
Molar Mass (K) = 39.098 g/mol
Molar Mass (Cl) = 35.453 g/mol
Molar Mass (KCl) = 39.098 g/mol + 35.453 g/mol
Molar Mass (KCl) = 74.551 g/mol
Now that you know the molar mass, you want to multiply it by the moles of KCl. This is possible because the molar mass is actually a ratio representing the relationship of grams and moles. In KCl, there are 74.551 grams of KCl for every 1 mole of KCl. When you are multiplying, make sure you set the ratio up in a way that allows for the units to cancel out and leave grams as your final answer.
3.80 moles KCl 74.551 g
----------------------- x ------------------- = 283 grams KCl
1 mole KCl
The final answer should have 3 sig figs because the value the problem gave (3.80 mol) also has 3 sig figs.
(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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with strong heating calcium carbonate undergoes thermal decomposition how many mole of CaCO3 are there in 50g of calcium carbonate
Answer:
a)CaCO 3→CaO+CO 2CaCO3→CaO+CO2
b) Moles of CaCO3=4.37moles
c) I) Mass of calcium oxide =28g
ii)Mass of carbon dioxide=16.7g
iii)Volume=203cm3
What is known about a reaction with a positive enthalpy?
A. Heat is given off as a product of the reaction.
B. The reaction has a large activation energy.
OC. Heat is required to make the reaction occur.
OD. The reaction will never be spontaneous.
Answer: C
Explanation:
In endothermic reactions, enthalpy is positive, and in exothermic reactions, enthalpy is negative, So, if enthalpy is positive, then it is an endothermic reaction, and hence is required for the reaction to occur.
which of the following symbol means a subtance is in water solutions?
a) (aq) b.) (w) c.) (s) d.) (I)
Answer:
a.) (aq)
Explanation:
(aq) means aqueous
so its in a solvent
the density of 190mg of a liquid is 0.0076g/cm calculate the volume in ml
[tex]\\ \rm\Rrightarrow Density=\dfrac{Mass}{Volume}[/tex]
[tex]\\ \rm\Rrightarrow Volume=\dfrac{Mass}{Density}[/tex]
[tex]\\ \rm\Rrightarrow Volume=\dfrac{0.19}{0.0076}[/tex]
[tex]\\ \rm\Rrightarrow Volume=25cm³[/tex]
[tex]\\ \rm\Rrightarrow Volume=25mL[/tex]
Which term is used to describe all the habitats around the world?
Ecosystem diversity
Genetic diversity
Natural selection
Species diversity
Answer:
ecosystem diversity
Explanation:
hope this helped