Answer:
B. People live longer than they used to
Explanation:
None of the other answers are correct.
Using standard heats of formation, calculate the standard enthalpy change for the following reaction.
4HCl(g) + O2(g)—>2H2O(g) + 2Cl2(g)
Answer:
ΔH°r = -114.40 kJ
Explanation:
Let's consider the following balanced equation.
4 HCl(g) + O₂(g) ⇒ 2 H₂O(g) + 2 Cl₂(g)
We can calculate the standard enthalpy change of the reaction (ΔH°r) using the following expression.
ΔH°r = ∑np × ΔH°f(p) - ∑nr × ΔH°f(r)
where
ΔH°f: standard heat of formation n: moles p: products r: reactantsΔH°r = 2 mol × ΔH°f(H₂O(g)) + 2 mol × ΔH°f(Cl₂(g)) - 4 mol × ΔH°f(HCl(g)) - 1 mol × ΔH°f(O₂(g))
ΔH°r = 2 mol × (-241.82 kJ/mol) + 2 mol × 0 kJ/mol - 4 mol × (-92.31 kJ/mol) - 1 mol × 0 kJ/mol
ΔH°r = -114.40 kJ
Arrange in terms of increasing atomic radius. From smallest to largest.
S, F, Sr, Na, Ga
Answer:
F<S<Na<Ga<Sr
Explanation:
Atomic radius increased from the right of the periodic table to left, and from the top to the down
8.8 Why do esters with higher molecular mass not have strong fragrances?
Answer:
Basically, fragrances reach other person through sense of smell. So, the strength of the fragrances depends a lot on its evaporation, which is strongly related to the boiling point. Esters with higher molecular weight do not have a strong fragrance because it has a higher boiling point.
which is expected to have a higher boiling point? why? CH3CH2OH or CH3CH2NH2
Answer:
Explanation: Ethanol, CH3CH2OH, has the highest of the three boiling points because it has the strongest dipole–dipole forces between molecules due to hydrogen bonding. ... Dimethyl ether, CH3OCH3, has the second- highest boiling point because it has dipole–dipole forces between molecules.
A gas made up of atoms escapes through a pinhole 0.392 times as fast as Ne gas. Write the chemical formula of the gas.
Answer: The chemical formula of the gas is Xenon.
Explanation:
From Graham's law of effusion rates, the rate of effusion of a gas is inversely proportional to the square root of its molar mass.
[tex]\frac{rate_1}{rate_2}=\sqrt{\frac{M_2}{M_1}}[/tex]
Given: Rate of unknown gas = [tex]0.392\times R_{Ne}[/tex]
Putting the values in the formula:
[tex]\frac{rate_X}{rate_{Ne}}=\sqrt{\frac{M_{Ne}}{M_X}}[/tex]
[tex]0.392=\sqrt{\frac{20.17}{M_X}}[/tex]
Squaring both sides:
[tex]0.154=\frac{20.17}{M_X}[/tex]
[tex]M_X=131g/mol[/tex]
As Xenon (Xe) has molar mass of 131g/mol, Thus the chemical formula of the gas is Xenon.
the moisturizer you see on the mirror in your bathroom after a hot shower is called?
Answer:
Soap that was thrown out
Write the chemical symbols for three different atomic cations that all have 14 protons.
Explanation:
The symbols for three different cations with 14 protons are Si²⁺, Si⁴⁺, and Si³⁺. An element with 14 protons must be silicon, Si. Its electron configuration is [Ne] 3s²3p², so it could lose up to four valence electrons. The most likely cations are Si²⁺, Si⁴⁺, and Si³⁺ (or Si⁺)
Who first proposed the concept of free energy?
a. Gibbs
b. Lavoisier
c. Dalton
d. Hess
Answer:
Hello There!!
Explanation:
The answer is=>a. Gibbs.
hope this helps,have a great day!!
~Pinky~
[tex]\huge{\textbf{\textsf{{\color{navy}{An}}{\purple{sw}}{\pink{er}} {\color{pink}{:}}}}}[/tex]
a. Gibbs
ThanksLenses are made to have different focal points. What two properties of a lens
affect the focal length?
A. Where the object is located
O B. Whether the image is virtual or real
O C. The material the lens is made from
O D. The centers of curvature of the two sides of the lens
The air bags in automobiles were once inflated by nitrogen gas generated by the rapid decomposition of
sodium azide, NaN3.
2 NaNz (s) 2 Na (s) + 3 N2 (g)
If an air bag has a volume of 53.4 L and is to be filled with nitrogen gas at a pressure of 1.07 atm and a
temperature of 23.7°C, how many moles of NaNz must decompose? You may assume the Ny behaves as
an ideal gas.
Answer:
1.57 mol NaN₃
Explanation:
2 NaN₃ (s) → 2 Na (s) + 3 N₂ (g)First we use PV=nRT to calculate the number of N₂ moles that need to be produced:
P = 1.07 atmV = 53.4 Ln = ?R = 0.082 atm·L·mol⁻¹·K⁻¹T = 23.7 °C ⇒ 23.7 + 273.16 = 296.86 KInputing the data:
1.07 atm * 53.4 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 296.86And solving for n:
n = 2.35 mol N₂Finally we convert N₂ moles into NaN₃ moles, using the stoichiometric coefficients of the balanced reaction:
2.35 mol N₂ * [tex]\frac{2molNaN_3}{3molN_2}[/tex] = 1.57 mol NaN₃Rain, snow, hail, and sleet are examples of
a
bad weather.
b condensation.
C precipitation.
d evaporation
Answer:
C. Precipitation
It made me put more on my answer.
Of the 8 planets, why does the sun have the most gravitational attraction to Mercury?
Answer:
It is the closest sir.
Have an amazing day and enjoy. P.S Good luck!
Explanation:
Let's chek the orders where mercury and rest planets present
MercuryVenusEarthMarsJupiterSaturnUranusNeptuneMercury is closest to sun so gravitational force is most
By which method the following mixture can be separated?(i)mixture of colours (ii) Minerals oil.
the answer ie the second option
Minerals oil
Why is it hard to predict the weather more than a few days in advance?
Answer:
Because the weather is complex and dynamic.
Explanation:
14
Select the correct answer.
A compound has an empirical formula of CzHs. What is true about this empirical formula?
O A.
It models the structure of the compound.
OB
It shows the ratio of elements in the compound.
O c. It gives the mass of each atom in the compound.
OD.
It indicates the number of atoms in the compound.
OE.
It describes only this one compound.
Reset
Next
Answer:
answer B
It shows the ratio of elements in the compound
Explanation:
Chemical formulas tell you how many atoms of each element are in a compound, and empirical formulas tell you the simplest or most reduced ratio of elements in a compound. If a compound's chemical formula cannot be reduced any more, then the empirical formula is the same as the chemical formula.
The statement which is true about the empirical formula is: It shows the ratio of elements in the compound. The correct option is B.
Empirical formula:
The empirical formula of a compound represents the simplest, most reduced ratio of the elements present in the compound.
The empirical formula represents the simplest whole-number ratio of atoms of each element present in a compound.
It is determined by dividing the subscripts of the compound's molecular formula by their greatest common divisor, which simplifies the ratio to its simplest form.
In the given empirical formula CzHs, "z" and "s" represent the subscripts indicating the number of carbon and hydrogen atoms, respectively.
Thus, the correct option is B.
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An unknown aqueous metal analysis yielded a detector response of 0.255. When 1.00 mL of a solution containing 100.0 ppm of the metal was mixed with 99.0 mL of the unknown, the detector signal increased to 0.502. Calculate the concentration of the metal in the unknown solution. Report your answer in ppm
Answer:
1.022ppm is the unknown concentration of the metal
Explanation:
Based on Lambert-Beer law, the increasing in signal of a detector is directly proportional to its concentration.
The unknown concentration (X) produces a signal of 0.255
99mL * X + 1mL * 100ppm / 100mL produces a signal of 0.502
0.99X + 1ppm produce 0.502, thus, X is:
0.255 * (0.99X + 1 / 0.502) =
X = 0.503X + 0.508
0.497X = 0.508
X =
1.022ppm is the unknown concentration of the metal
Hydrochloric acid reacts with sodium hydroxide to produce sodium chloride and water. If 20.6 g of sodium hydroxide reacts with an excess of hydrochloric acid, how many grams of sodium chloride are produced? HCl + NaOH → NaCl + H2O
Answer:
30.1 g NaCl
Explanation:
Your first conversion is converting grams NaOH to moles of NaOH using its molar mass (39.997 g/mol). Then, use the mole ratio of 1 mol NaCl for every 1 mol NaOH to get to moles of NaCl. Then finally multiply by the molar mass of NaCl (58.44 g/mol) to get grams of NaCl.
20.6 g NaOH • (1 mol NaOH / 39.997 g NaOH) • (1 mol NaCl / 1 mol NaOH) • (58.44 g NaCl / 1 mol NaCl) = 30.1 g NaCl
Which soil horizon contains the most organic matter?
A horizon
B horizon
C horizon
D horizon
Answer:
I- It says horizon so.....what....wth ._.
Explanation:
The force of gravity from Earth to Mars is___
a. less than the force of gravity from Mars to Earth.
b. equal to the force of gravity from Mars to Earth.
less than the force of gravity from mars to earth
8. A train travels at a at a speed of 30 miles per hour if 1 mile = 1.6 kilometers, how fast is the train traveling in kilometers per minute?
A. 0.8 km/min
B. 1.0 km/min
C. 0,4 km/min
D. 0,6 km/min
Answer:
Explanation:
A: 0.8 KM/Min
1.6 x 30 = 48
48/60 = 0.8
Which of the following is an example of a physical property?
A- Luminol reacting with blood stains to create a faint light
B- Bleach changing the color of a Ph test strip
C- The thickness of glass shards from a crime scene
D- Heroin turning purple when it is exposed to Marquis reagent
Answer:
The answer is C
Explanation:
It just makes the most sense to me
Many scientists think human cloning is possible, so why haven't we made human clones yet?
Question 5 options:
There is not enough medical supplies to clone a human
Human cloning is extremely controversial and many people believe it is unethical
Scientists have determined that stem cells would not be beneficial to human cloning
The human genome is too complex to clone
Answer:
GIVEN IT'S A MULTI CHOICE QUESTION:
1. False
2. True
3. False
4. True
IF ITS NOT
2
Explanation:
We haven't made human clones because human cloning is extremely controversial and many people believe it is unethical.
What is cloning?Cloning is a genetic technique that can be used to reproduce genetically identical organisms in a laboratory.
Human cloning refers to the generation of genetically identical humans in the laboratory.Human cloning can be considered unethical because a person has the right to have an identity, and the cloning technique faces this principle.In conclusion, we haven't made human clones because human cloning is extremely controversial and many people believe it is unethical.
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Which of the following best describes careers that use chemistry?
A. Careers that involve scientific research or chemistry instruction
B. Only careers that involve scientific research
C. Only careers that involve chemical manufacturing
D. A variety of careers in many different industries
Answer:
D
Explanation:
Methane (CH4) undergoes combustion. Which products form? please help will give brainliest if correct
Answer:
B. CO₂ and H₂O.
Explanation:
When any organic substance undergoes complete combustion, it produces carbon dioxide (CO₂) and water (H₂O).
In the case of methane, the balanced reaction is:
CH₄ + 2O₂ → CO₂ + 2H₂OWith the above information in mind the correct answer is option B. CO₂ and H₂O.
When the combustion is incomplete, carbon monoxide (CO) is produced as well.
Answer:
B. CO₂ and H₂O!
Why are weather front boundaries turbulent?
Answer:
Answer Below Hope Its Correct.
Explanation:
A weather front is a transition zone between two different air masses at the Earth's surface. Each air mass has unique temperature and humidity characteristics. Often there is turbulence at a front, which is the borderline where two different air masses come together. The turbulence can cause clouds and storms.
Instead of causing clouds and storms, some fronts just cause a change in temperature. However, some storm fronts start Earth's largest storms. Tropical waves are fronts that develop in the tropical Atlantic Ocean off the coast of Africa. These fronts can develop into tropical storms or hurricanes if conditions allow.
Fronts move across the Earth's surface over multiple days. The direction of movement is often guided by high winds, such as Jet Streams. Landforms like mountains can also change the path of a front.
There are four different types of weather fronts: cold fronts, warm fronts, stationary fronts, and occluded fronts.
How do you know a chemical reaction has occurred?
Answer:
To tell if a chemical reaction has occurred look at its color change, temperature change, Precipitate formation, gas production, and light emission.
When is energy released during a chemical reaction?
A. when chemical bonds break and form
B. when chemical bonds form
C. when chemical bonds break
“Don’t click links if answers have one!”
Help please science questions
It’s for 20 points
Answer:
1 , 2 , 3
Explanation:
Answer
Contributed by Paul Flowers, Klaus Theopold & Richard Langley et al.
General Chemistry at OpenStax CNX
Learning Objectives
Outline the general approach for the isolation of transition metals from natural sources
Describe typical physical and chemical properties of the transition metals
Identify simple compound classes for transition metals and describe their chemical properties
We have daily contact with many transition metals. Iron occurs everywhere—from the rings in your spiral notebook and the cutlery in your kitchen to automobiles, ships, buildings, and in the hemoglobin in your blood. Titanium is useful in the manufacture of lightweight, durable products such as bicycle frames, artificial hips, and jewelry. Chromium is useful as a protective plating on plumbing fixtures and automotive detailing.
In gas chromatography, the stationary phase is made up of high molecular weight non-volatile polymer coated on solid support packed inside a column and the mobile phase is an inert gas that carries the volatilized components of the sample mixture through the column toward the detector. The physical form of the stationary (s) and mobile phase (m) in gas chromatography are:
Answer:
liquid (s), gas (m)
Explanation:
In gas chromatography, the phase of stationary would be made of great molecular weight that have non-volatile coated on the packed i.e. inside a column also the mobile phase represent the inert gas that carries the components that should be volatilized.
Now the physical form and the mobile phase is the liquid and the gas
The same would be relevant and considered too
How many grams of Mg(NO3), are necessary to
make 1500 mL of a 0.50 M solution?
Answer:
1.1 × 10² g
Explanation:
Step 1: Given data
Concentration of the solution (C): 0.50 M (0.50 mol/L)Volume of solution (V): 1500 mL (1.500 L)Step 2: Calculate the moles of Mg(NO₃)₂ (solute)
Molarity is equal to the moles of solute (n) divided by the liters of solution.
C = n/V
n = C × V
n = 0.50 mol/L × 1.500 L = 0.75 mol
Step 3: Calculate the mass corresponding to 0.75 moles of Mg(NO₃)₂
The molar mass of Mg(NO₃)₂ is 148.3 g/mol.
0.75 mol × 148.3 g/mol = 1.1 × 10² g