问题2
15
The reaction causes the temperature of its surroundings to decrease is
therefore heat is
by the reaction.
and
Select the two words that best complete this sentence.
a. endothermic, absorbed
b. exothermic, released
c. exothermic, absorbed
d. endothermic, released
Answer:
a endothermic, absorbed
Calculate the number of hydrogen atoms present in 40g of urea, (NH2)2CO
Answer: There are [tex]16.14 \times 10^{23}[/tex] atoms of hydrogen are present in 40g of urea, [tex](NH_{2})_{2}CO[/tex].
Explanation:
Given: Mass of urea = 40 g
Number of moles is the mass of substance divided by its molar mass.
First, moles of urea (molar mass = 60 g/mol) are calculated as follows.
[tex]Moles = \frac{mass}{molar mass}\\= \frac{40 g}{60 g/mol}\\= 0.67 mol[/tex]
According to the mole concept, 1 mole of every substance contains [tex]6.022 \times 10^{23}[/tex] atoms.
So, the number of atoms present in 0.67 moles are as follows.
[tex]0.67 mol \times 6.022 \times 10^{23} atoms/mol\\= 4.035 \times 10^{23} atoms[/tex]
In a molecule of urea there are 4 hydrogen atoms. Hence, number of hydrogen atoms present in 40 g of urea is as follows.
[tex]4 \times 4.035 \times 10^{23} atoms\\= 16.14 \times 10^{23} atoms[/tex]
Thus, we can conclude that there are [tex]16.14 \times 10^{23}[/tex] atoms of hydrogen are present in 40g of urea, [tex](NH_{2})_{2}CO[/tex].
1. For the reaction 3A — C, the initial concentration of A was 0.2 M, and the reaction rate was
1.0 M/s. When [A] was doubled, the reaction rate increased to 4.0 M/s. Determine the rate
law for the reaction.
Answer:
[tex]r=25M^{-1}s^{-1}[A]^2[/tex]
Explanation:
Hello there!
In this case, according to the given information for this chemical reaction, it is possible for us to set up the following general rate law and the ratio of the initial and the final (doubled concentration) condition:
[tex]r=k[A]^n\\\\\frac{r_1}{r_2} =\frac{k[A]_1^n}{k[A]_2^n}[/tex]
Next, we plug in the given concentrations of A, 0.2M and 0.4 M, the rates, 1.0 M/s and 4.0 M/s and cancel out the rate constants as they are the same, in order to obtain the following:
[tex]\frac{1.0}{4.0} =\frac{0.2^n}{0.4^n}\\\\0.25=0.5^n\\\\n=\frac{ln(0.25)}{ln(0.5)} \\\\n=2[/tex]
Which means this reaction is second-order with respect to A. Finally, we calculate the rate constant by using n, [A] and r, to obtain:
[tex]k=\frac{r}{[A]^n} =\frac{1.0M/s}{(0.2M)^2}\\\\k=25M^{-1}s^{-1}[/tex]
Thus, the rate law turns out to be:
[tex]r=25M^{-1}s^{-1}[A]^2[/tex]
Regards!
PLEASE HELP ME!!!!!!!
Answer:
The heat capacity of the metal underneath the gold is 0.431 J/g°C
Explanation:
Using the formula as outlined in the image:
Q = m × c × ∆T
Where;
Q = amount of heat energy (J)
m = mass of substance (g)
c = specific heat capacity (J/g°C)
∆T = change in temperature (°C)
According to the information in this question;
Q = 503.9J
m = 23.02g
c = ?
∆T = 74°C - 23.2°C = 50.8°C
Using Q = m × c × ∆T
c = Q ÷ m∆T
c = 503.9 ÷ (23.02 × 50.8)
c = 503.9 ÷ 1169.42
c = 0.431 J/g°C
From the above heat capacity of the metal underneath the gold, it is obvious that the metal is not pure gold (c = 0.129J/g°C)
HELP PLZ
Calculate the percent composition by mass of iron in Fe(NO3)3
What is the [OH-] in a solution if the [H*] = 1.2 x 10-3 M?
We know that [OH⁻] * [H⁺] = 10⁻¹⁴
plugging the value of [H⁺]
[OH⁻] * 1.2 * 10⁻³ = 10⁻¹⁴
[OH⁻] = 10⁻¹⁴ * (10³/1.2)
[OH⁻] = 833.3 * 10⁻¹⁴
[OH⁻] = 8.33 * 10⁻¹²
What transition energy corresponds to an absorption line at 460 nm?
A. 6.52 x 10-19 J
B. 4.32 x 10-19 J
C. 4.45 x 10-19 J
D. 2.31 x 10-19 J
Answer:
B. 4.32 x 10-19 J is correct via a p e x
Explanation:
Now we need to find the amount of NF3 that can be formed by the complete reactions of each of the reactants. If all of the N2 was used up in the reaction, how many moles of NF3 would be produced
The question is incomplete, the complete question is:
Nitrogen and fluorine react to form nitrogen fluoride according to the chemical equation:
[tex]N_2(g)+3F_2(g)\rightarrow 2NF_3(g)[/tex]
A sample contains 19.3 g of [tex]N_2[/tex] is reacted with 19.3 g of [tex]F_2[/tex]. Now we need to find the amount of [tex]NF_3[/tex] that can be formed by the complete reactions of each of the reactants.
If all of the [tex]N_2[/tex] was used up in the reaction, how many moles of [tex]NF_3[/tex] would be produced?
Answer: 1.378 moles of [tex]NF_3[/tex] are produced in the reaction.
Explanation:
The number of moles is defined as the ratio of the mass of a substance to its molar mass.
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
Limiting reagent is defined as the reagent which is completely consumed in the reaction and limits the formation of the product.
Excess reagent is defined as the reagent which is left behind after the completion of the reaction.
In the given chemical reaction, [tex]N_2[/tex] is considered as a limiting reagent because it limits the formation of the product and it was completely consumed in the reaction.
We are given:
Mass of [tex]N_2[/tex] = 19.3 g
Molar mass of [tex]N_2[/tex] = 28.02 g/mol
Putting values in equation 1:
[tex]\text{Moles of }N_2=\frac{19.3g}{28.02g/mol}=0.689mol[/tex]
For the given chemical reaction:
[tex]N_2(g)+3F_2(g)\rightarrow 2NF_3(g)[/tex]
By the stoichiometry of the reaction:
1 mole of [tex]N_2[/tex] produces 2 moles of [tex]NF_3[/tex]
So, 0.689 moles of [tex]N_2[/tex] will produce = [tex]\frac{2}{1}\times 0.689=1.378mol[/tex] of [tex]NF_3[/tex]
Hence, 1.378 moles of [tex]NF_3[/tex] are produced in the reaction.
If 1.00 mol of an ideal monatomic gas initially at 74 K absorbs 100 J of thermal energy, what is the final temperature
Answer:
T = 82 K
Explanation:
The computation of the final temperature is shown below;
Given that
T_0 denotes the initial temperature of the gas i.e. 74 K
T denotes the final temperature of the gas = ?
n denotes number of moles of monoatomic gas i.e. 1.00 mol
R denotes universal gas constant = 8.314
c denotes the heat capacity at constant volume i.e.
= (1.5) R = (1.5) (8.314)
= 12.5
Q denotes the Amount of heat absorbed i.e 100 J
We know that
Amount of heat absorbed is provided as
Q = n c (T - T_0)
100 = (1) (12.5) (T - 74)
T = 82 K
A radioactive material, with half-life of six months, has 100 thousand unstable nuclei.
(a) Find the number of unstable nuclei present after three months.
(b) What will be its activity at this time (after three months)?
Answer:
See Explanation
Explanation:
Given that;
N/No = (1/2)^t/t1/2
Where;
No = amount of radioactive isotope originally present
N = A mount of radioactive isotope present at time t
t = time taken
t1/2 = half life
N/1000=(1/2)^3/6
N/1000=(1/2)^0.5
N = (1/2)^0.5 * 1000
N= 707 unstable nuclei
Since the value of the initial activity of the radioactive material was not given, the activity of the radioactive material after three months is given by;
Decay constant = 0.693/t1/2 = 0.693/6 months = 0.1155 month^-1
Hence;
A=Aoe^-kt
Where;
A = Activity after a time t
Ao = initial activity
k = decay constant
t = time taken
A = Aoe^-3 *0.1155
A=Aoe^-0.3465
Write a conclusion statement that addresses the following questions: • Explain what the color change indicated about the changes in the concentrations of Co(H2O)62+ and CoCl42– in each trial. • Do your data support or fail to support your hypothesis (include examples)? • How do you think the investigation can be explored further?
When the concentration of the HCl is varied, the color of the solution is changed as the equilibrium position moves to the left or right.
What is equilibrium?The term equilibrium in a chemical reaction connotes that the forward and the revers reactions proceed at the same rate. Let us note that Co(H2O)6^2+ is pink in color while CoCl4^2– is blue in color.
As such, when the concentration of the HCl is varied, the color of the solution is changed as the equilibrium position moves to the left or right.
Learn more anout equilibrium: https://brainly.com/question/365923
Which waves are blocked by the atmosphere? A. gamma rays B. visible light C. radio waves D. infrared waves
Answer: look at the explanation and try to work it
Explanation: in contrast, our atmosphere blocks most ultraviolet light (UV) and all X-rays and gamma-rays from reaching the surface of Earth. Because of this, astronomers can only study these kinds of light using detectors mounted on weather balloons, in rockets, or in Earth-orbiting satellites.
Concentrated aqueous perchloric acid is 70.5 wt% HClO4 and has a concentration of 11.7 M. Calculate the volume of concentrated perchloric acid that should be diluted to 1.90 L to form a 5.00 M HClO4 solution.
Answer:
0.812 L
Explanation:
As this is a dilution process problem, we can solve it by using the C₁V₁ = C₂V₂ formula, where in this case:
C₁ = 11.7 MV₁ = ?C₂ = 5.00 MV₂ = 1.90 LWe input the data:
11.7 M * V₁ = 5.00 M * 1.90 LAnd solve for V₁:
V₁ = 0.812 LThis means that 0.812 L of concentrated perchloric acid should be diluted to a final volume of 1.90 L.
What is the main function of a nucleic acid?
A. It allows polysaccharides to form.
OB. It stores lipids inside the proteins.
C. It contains instructions for making proteins.
OD. It is a catalyst in chemical reactions.
The main function of nucleic acid is It stores lipids inside the proteins.
Nucleic acidsNucleic acids are large biomolecules that play essential roles in all cells and viruses. A major function of nucleic acids involves the storage and expression of genomic information. Deoxyribonucleic acid, or DNA, encodes the information cells need to make proteins. A related type of nucleic acid, called ribonucleic acid (RNA), comes in different molecular forms that play multiple cellular roles, including protein synthesis.
Nucleic acids are made of nitrogen-containing bases, phosphate groups, and sugar molecules. Each type of nucleic acid has a distinctive structure and plays a different role in our cells. Researchers who first explored molecules inside the nucleus of cells found a peculiar compound that was not a protein or a lipid or a carbohydrate. It was new. The discovery of this molecule — nuclein, which upon further understanding became nucleic acid — set in motion the eventual discovery of DNA.
Learn more about Nucleic acids
https://brainly.com/question/2488520
#SPJ2
What type of intermolecular forces are due to
the attraction between temporary dipoles
and their induced temporary dipoles?
Select one:
a. London dispersion
b. Metallic bond
C. Covalent bond
d. Hydrogen bond
e. lonic bond
Answer:
A. London dispersion
Explanation:
London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.
The intermolecular forces are due to the attraction between temporary dipoles, and their induced temporary dipoles are the type of London dispersion force. Therefore, option A is correct.
What is london dispersion force ?When the electrons in two nearby atoms occupy positions that cause the atoms to temporarily form dipoles, the consequence is the London dispersion force, a transient attractive force. The term "induced dipole-induced dipole attraction" is frequently used to describe this effect.
The electron density of a molecule is redistributed towards another molecule because the electrons in nearby molecules "flee" when they repel one another. This is typically explained as the instantaneous production of attracted dipoles.
The material's atomic or molecular weight affects the London dispersion forces. More electrons and stronger London forces are present in heavier atoms or molecules. They are therefore more difficult to melt or boil.
Thus, option A is correct.
To learn more about london dispersion force, follow the link;
https://brainly.com/question/20514601
#SPJ2
How many moles of MgCO3 are present in 252.939 grams of MgCO3?
A. 2
B. 3
C.5
D.6
Answer:
Hello, I was doing this and from my caluclations it should be :
Explanation:
3 Moles.
The three moles of MgCO3 are present in 252.939 grams of MgCO3.
So, option B is correct one .
What is molar mass?The molar mass of substance is equal to mass of one mole of that substance.
Example: Molar mass of MgCO3 is equal to mass of one mole of MgCO3.
Molar mass of Mg = 24.305 u
Molar mass of C = 12.011 u
Molar mass of O = 15.999 u
Molar mass of MgCO3 = Molar mass of Mg + Molar mass of C + Molar mass of O*3
Molar mass of MgCO3 = 24.305 + 12.011 + 15.999 * 3
Molar mass of MgCO3 = 84.3139 gram
Molar mass of MgCO3 contain 84.3139 gram
So, 252.939 grams of MgCO3 = 252.939 grams/84.3139 gram
252.939 grams of MgCO3 = 2.999 moles
To learn more about moles here.
https://brainly.com/question/26416088
#SPJ3
The compound aluminum nitride () is a compound semiconductor having mixed ionic and covalent bonding. The electronegativities for and are 1.5 and 3.0 respectively. Calculate the fraction of the bonding that is ionic.
Answer:
Fraction ionic = 0.43
Explanation:
To solve this question, we must, as first, find the fraction of the bond that is covalent using the equation:
Fraction Covalent = exp (-0.25*(Enitride - EAl)²)
Fraction covalent = exp (-0.25*(3.0- 1.5)²)
Fraction covalent = exp (-0.25*2.25)
Fraction covalent = exp (-0.5625)
Fraction covalent = 0.57
As:
1 = Fraction Covalent + Fraction Ionic:
Fraction ionic = 1 - 0.57
Fraction ionic = 0.43
You need to prepare 1 L of the citric acid/citrate buffer. You have chosen to use Method 1 (see lab presentation). Calculate the pH of a solution prepared by mixing 300 mL of 0.45 M citric acid acid and 100 mL of 0.65 M NaOH plus water to a final volume of one liter. The Ka of citric acid is 7.24 x 10-4.
Answer:
3.11 is the pH of the buffer
Explanation:
The pH of a buffer is obtained using H-H equation:
pH = pKa + log [Conjugate base] / [Weak acid]
Where pH is the pH of the buffer, pKa = -log Ka = 3.14 for the citric buffer and [] could be taken as the moles of each species.
The citric acid,HX (Weak acid), reacts with NaOH to produce sodium citrate, NaX (weak base) and water:
HX + NaOH → H2O + NaX
That means the moles of NaOH added = Moles of sodium citrate produced
And the resulitng moles of HX = Initial moles - Moles NaOH added
Moles HX and NaX:
Moles NaOH = 0.100L * (0.65mol / L) = 0.065 moles NaOH = Moles NaX
Moles HX = 0.300L * (0.45mol / L) = 0.135 moles HX - 0.065 moles NaOH = 0.070 moles HX
Replacing in H-H equation:
pH = 3.14 + log [0.065mol] / [0.070mol]
pH = 3.11 is the pH of the buffer
How many Grams of NO is produced if 12g of O2 is combined with excess ammonia?
Answer:
9g
Explanation:
moles O2 = mass / Mr = 12 / 2(16.0) = 0.375
ratio O2 : NO = 5:4
moles NO produced = 0.375 * 4/5 = 0.3
mass NO = Mr * mol = (14.0+16.0) * 0.3 = 9g
The Grams of NO is produced if 12g of O2 is combined with excess ammonia is 80 gram.
What is NO?The full form of NO is nitrogen oxide Nitrogen belong to the 15th group of the periodic table with molar mass of 14 and oxygen belong to the 16th group of the periodic table.
In the given their are 4 molecules of each nitrogen and oxygen and mass of O2 is given whereas, mass of nitrogen for 4 molecule will be 56 gram.
Grams of NO = 14 × 4 + 12 × 2
Grams of NO = 80 grams.
Therefore, the mass of NO for the given reaction is combined with excess ammonia is 80 gram.
Learn more about NO, here;
https://brainly.com/question/1178944
#SPJ2
The specific heat of palladium is 0.239 J/g°C. How much heat (q) is released when a 10.0 g piece of platinum cools from 100.0°C to 50.0°C?
Answer:
119.5 J
Explanation:
First we calculate the temperature difference:
ΔT = 100 °C - 50 °C = 50 °CThen we can calculate the heat released by using the following formula:
q = Cp * ΔT * mWhere q is the heat, Cp is the specific heat, ΔT is the temperature difference and m is the mass.
We input the data:
q = 0.239 J/g°C * 50 °C * 10.0 gq = 119.5 JA sample of aluminum absorbed 9.86 J of heat and its temperature increased from 23.2 and 30.5 degrees * C . What is the mass of the aluminum? Th specific heat of aluminum is 0.902 J/g^ C . Round your answer to 2 significant figures. Do not include units in your answer. *
Explanation:
H=mc×∆©
9.86=m×0.902×(30.5-23.2)
m=1.5
Explanation:
The specific heat of a substance is the amount of heat required to raise the temperature of 1 gram of the substance by 1 degree Celsius. The formula for calculating the heat absorbed or released by a substance is `q = mcΔT`, where `q` is the heat absorbed or released, `m` is the mass of the substance, `c` is the specific heat of the substance, and `ΔT` is the change in temperature.
In this case, we can use this formula to solve for the mass of the aluminum sample. We know that `q = 9.86 J`, `c = 0.902 J/g°C`, and `ΔT = 30.5°C - 23.2°C = 7.3°C`. Plugging these values into the formula, we get:
`9.86 J = m * 0.902 J/g°C * 7.3°C`
Solving for `m`, we find that the mass of the aluminum sample is approximately `1.5 g`, rounded to 2 significant figures.
PLEASE mark as Brainliest
write 5 acid and 5 akalis
Answer:
5 Acids
Chemical
- Hydrochloric acid in gastric juice
- Sulphuric acid
- Nitric acid
- Uric acid
- Acetic acid
Household
- Vinegar
- Lemon
- Milk
- Batteries
- Soft drinks
5 Alkali
Household
- Dishwashwer soaps
- Detergents
- Toothpaste
- Oven cleaner
- Alkaline batteries
- Sodium bicarbonate
Chemicals
- Sodium hydroxide or lye
- Calcium carbonate (limestone)
- Ammonium hydroxide
- Calcium hydroxide
What mass of HF is produced according to the given equation when 2.397 grams of each reactants are combined?
CaF2 + H2SO4 --> CaSO4 + 2HF
+HF is the answer
Explanation:
How many moles are 2.60 * 10 ^ 27 atoms of Silicon?
Answer:
~4,317.5 moles of Silicon
Explanation:
Using Avogadro's contant we know that:
1mole = 6.022 x 10^23 atoms
So,to calculate the number of moles in 2.60 x 10^27 atoms of Silicon:
=(2.60 x 10^27 x 1)/(6.022 x 10^23)
~4,317.5 moles of Silicon
Hope it helps:)
The area of a telescope lens is 6507 x 10^3 mm^2. What is the area in square feet, enter your answer in scientific notation. If it takes a technician 51.6 s to polish 1.68 x 10^2 mm^2 how long does it take her to polish the entire lens ?
Answer: the area of the telescope lens is \textit{0,08507 ft}
Explanation: Happy I could help!
A gas stp is 4.38 L how many moles are there ?
Answer:
There are 0.195 moles.
Explanation:
1 mol of any gas under STP (meaning 1 atm and 273 K) will occupy 22.4 liters.
With the information above in mind, we can calculate how many moles will occupy 4.38 liters:
4.38 L * 1 mol / 22.4 L = 0.195 molIn 4.38 liters of a gas at STP there will be 0.195 moles.
True or False: "Endothermic Reactions absorbs energy in the form of heat."
Answer:
true
Explanation:
Endo means inside
but exo means outside
an Endo thermic reaction sounds like it wouldn't be the one to give off heat, so it might be storing heat.
explain the trend in boling point of alcohols in their homologous series
Explanation:
The boiling point of alcohols also increase as the length of hydrocarbon chain increases
The boiling point of alcohols also increase as the length of hydrocarbon chain increases.
Why boiling points of alcohols increases as the length of hydrocarbon chain increasesSince, boiling point depends upon type of bonds present in the molecules.If molecules have hydrogen bonding then boiling point is higher than others because hydrogen bond is stronger bond.So, higher energy or temperature required to break these bond or overcomes the inter molecular force of attraction.Since, alcohol contains hydrogen bonding. So, its boiling points are higher as compare to other compounds.Since, boiling points is also directly proportional to molar mass of molecules. So, molecule have higher molar mass has comparatively high boiling point.Example: An alcohols with lower hydrocarbon chain has lower boiling points as compare to alcohols with higher hydrocarbon chain.To learn more about alcohols,
https://brainly.com/question/4698220
#SPJ2
What mass of oxygen will react with 2.64 g of magnesium?
2Mg(s) + O2(g) → MgO(s)
Answer:
[tex](24 \times 2) \: g \: of \: magnesium \: reacts \: with \: (16 \times 2) \: g \: of \: oxygen \\ 2.64 \: g \: of \: magnesium \: will \: react \: with \: ( \frac{2.64 \times 16 \times 2}{24 \times 2} ) \: g \\ = 1.76 \: g \: of \: oxygen[/tex]
cloruro de litio mas sodio
Answer:
El cloruro de litio se utiliza para fabricar litio metálico. El cloruro de litio se funde y electroliza. Esto produce litio metálico líquido.
Explanation:
sowwy si mi español es malo
Answer:
give him brainliest
Explanation: