Answer:
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What is the natural phenomenon that moves the
cough droplets through the air?
Answer:
For a mild human cough in air at 20 °C and 50% relative humidity, we found that ... larger droplets are dispersed into smaller ones gradually while moving away from the ... Complex phase change and transport phenomena such as evaporation and ... Natural Ventilation for Infection Control in Health-Care Settings
Explanation
Answer in the correct significant figures: 9.66 / 0.33
HELP! What is a pure substance salt or seawater???? PLEASE HELP ME!
Answer:
Your answer is salt. Pure substances are made of materials with one type of molecule. Seawater has salt and water molecules, which is more than one, so your answer is salt.
Hope this helps!
chemical synthesis of drugs allowed development of cancer treatments that save lives
Answer:yes
Explanation:
please someone should explain gas laws to me
Answer:
Gas laws, Laws that relate the pressure, volume, and temperature of a gas. ... These two laws can be combined to form a single generalization of the behavior of gases known as an equation of state, PV = nRT, where n is the number of gram-moles of a gas and R is called the universal gas constant.
Explanation:
Hope it helps
As the mass of a sample increases, the number of moles present in the sample
Answer:
increases
Explanation:
Answer: will also increase
Explanation:
If the mass in a sample increases, the number of molecules will also increase. Hope this helps!
Ethylene glycol (C2H6O2) is used as an antifreeze in cars. If 400 g of ethylene glycol is added to 4.00 kg of water, what is the molality? Calculate how much the freezing point of water will be lowered. The freezing-point depression constant for water is Kf = –1.86°C/m.
Answer:
The freezing point of water will be lowered 3°C
Explanation:
Remember that molality is generally the standard for calculating the concentration, between molarity and molality. In this question we have to apply molality, given the units as moles and kilograms.
We can start by receiving the molality of this solution through the following formula...
[tex]\mathrm{m}=\mathrm{(mass}\mathrm{/molar\:mass)} * (1000/\mathrm{mass\:of\:solvent)},[/tex]
[tex]\mathrm{m} =\mathrm{(400.0 g / 62.07 g/mol) * (1000 / 4000.0 g)},[/tex]
[tex]\mathrm{m} = (400/62.07) * (1000 / 4000) = \left(\frac{400}{62.07}\right)\left(\frac{1000}{4000}\right) = \frac{1000}{620.7} = 1.61108\dots\mathrm{m}[/tex]
Now we can determine how much the freezing point of water will be lowered, given that the freezing-point depression constant for water is Kf= –1.86°C/m. Remember that " Kf " is the final temperature, so to determine how much the temperature of the water will decrease, we can note the change in temperature...
[tex]\mathrm{change\:in\:temperature} = ( - 1.86\mathrm{C/m})(1.61\mathrm{m}) = - 1.86 * 1.61 = -2.9946[/tex]
[tex]-2.9946 = \mathrm{About\:-3C}[/tex]
Hence the freezing point of water will be lowered 3°C.
Which statement regarding serum magnesium (Mg ++) is true? (Select all that apply.) Alcohol-related diseases frequently cause low Mg+ levels. Vomiting is not generally seen as a major cause of Mg+ loss. Mg++ levels present similarly to calcium (Ca++) levels in the blood. Mg+ deficiencies often result in low serum potassium (K+) levels. Mg+ deficiencies must be treated before potassium (K+) deficiencies.
Answer:
-
Alcohol-related diseases frequently cause low Mg+ levels.
- Mg+ deficiencies must be treated before potassium (K+) deficiencies.
- Mg+ deficiencies often result in low serum potassium (K+)
- Mg++ levels present similarly to calcium (Ca++) levels in the blood.
- Vomiting is not generally seen as a major cause of Mg+ loss
You are attempting to determine the thermodynamic properties of an unknown compound. You’ve already determined delta H fusion to be 5.56 kJ/mol and delta H vaporization to be 21.99 kJ/mol. In one of these previous experiments, 2.56 g of this compound was placed in a glass bulb and vaporized by placing the glass bulb into 200. g of hot water initially at 68.25 degrees Celsius, which resulted in a final water temperature of 67.91 degrees Celsius. You are now attempting to determine the enthalpy of solution of this compound. To this end, you dissolve 55.6 g of this compound in 495 g of water initially at 25.2 degrees Celsius. The final temperature of the solution is 19.4 degrees Celsius. What is the enthalpy of solution of this compound in kJ/mol?
Answer:
The heat of solution of the compound = 42.75 kJ/mol
Explanation:
Here we have;
The heat of vaporization = 21.99 kJ/mol
2.56 g of the compound is then placed in 200 g. of water
The temperature of the water reduces from 68.25°C to 67.91°C
The specific heat capacity of water = 4.19 kJ/kg = 4.19 J/g
Mass of the water = 200 g
Heat lost by the water ΔH = m × c × Δθ = n × ΔH vaporization of the compound
Where;
m = The mass of the water = 200 g
c = The specific heat capacity of water = 4.19 kJ/kg = 4.19 J/g
Δθ = The change in temperature = 68.25°C - 67.91°C = 0.34°C
n = The number of moles of the compound
ΔH = m × c × Δθ = 200×4.19×0.34 = 284.92 J = 0.28492 kJ
∴ n × ΔH vaporization of the compound = 0.28492 kJ
n = 0.28492 kJ/( ΔH vaporization of the compound) = 0.28492/21.99≈0.013 moles
∴ 2.56 g = 0.013 moles
1 mole = The molar mass of the compound = 2.56/0.013= 197.6 g/mol
Therefore;
The number of moles in 55.6 g of the compound = 55.6/197.6 = 0.2814 moles
The heat given by the water = ΔH = 495 × (25.2 - 19.4) × 4.19 = 12029.49 J
Therefore;
0.2814 × ΔH(solution) = 12029.49 J = 12.02949 kJ
ΔH(solution) = 12.02949/0.2814 = 42.75 kJ/mol
The heat of solution of the compound = 42.75 kJ/mol.
What is the iupac name of this structure?
Answer:
3–ethyl–4–methylhexane.
Explanation:
To name the above compound, do the following:
1. Determine the functional group of the compound.
2. Locate the longest continuous carbon chain. This gives the parent name of the compound.
3. Identify the substituent group attached to the compound.
4. Give the substituent the lowest possible count.
5. Combine the above to name the compound.
Now, we shall name the compound given in the question above as follow:
1. The compound contains only single bond. Therefore, the compound belong to the alkane family.
2. The longest continuous carbon chain is 6 i.e hexane.
3. The substituent group attached are:
i. Methyl, CH3.
ii. Ethyl, CH2CH3.
4. we shall name the substituents alphabetically i.e ethly will come before methyl. Therefore,
Ethyl is located at carbon 3.
Methy is located at carbon 4.
5. Therefore, the name of the compound is:
3–ethyl–4–methylhexane.
5) What is the empirical formula of a compound containing 47.37% carbon, 10.59% hydrogen, and 42.04% oxygen?
Answer:
C2H4O
two atoms of carbon four atoms of hydrogen and one atom of oxygen
does the atomic mass come from the masses of both protons and electron
Answer:
no
Explanation:
For any given isotope, the sum of the numbers of protons and neutrons in the nucleus is called the mass number. This is because each proton and each neutron weigh one atomic mass unit . By adding together the number of protons and neutrons and multiplying by 1 , you can calculate the mass of the atom.
Answer:
No
Explanation:
An element's mass number (A) is the sum of the number of protons and the number of neutrons. Protons and neutrons both weigh about one atomic mass unit or amu. Isotopes of the same element will have the same atomic number but different mass numbers.
The atoms and molecules in a liquid are in constant motion. As temperature decreases, what is true of the particles in the liquid? (5 points)
Oa
The distance between the particles increases.
The attraction between the particles decreases.
Ob
Ос
The rate of partide movement decreases.
Od
The potential energy of the particles decreases
Answer:
A
Explanation:
Answer:
The distance between the particles increases
25,000cg is equal to _g
Answer:
250 g
Explanation:
Convert 7.72 years into days.
Answer:2817.8
Explanation:multiply the value by 365
Explanation:
7.72 x 365= 2817.8 days
What gas makes up 73% of earth's atmosphere?
Answer: nitrogen
Explanation:
3 Select the correct answer. Which unit can be used to express the rate of a reaction? A. mL / s B. mL / g C. g / mL D. mL / mol E. s / mL Reset Next
Answer:
A) mL / s
Explanation:
ΔH for the reaction below is -826.0 kJ/mol. Calculate the heat change when a 69.03-g sample of iron is reacted.4Fe(s) + 3 O2(g) --> Fe2O3(s)a. - 255.2 kJb. -510.5 kJc. -1020.9 kJd. -2042 kJe. -2.851 x 10^4 kJ
Answer:
c. -1020.9 kJ
Explanation:
4Fe (s) + 3 O₂ (g) --> 2 Fe₂O₃(s) ΔH = -826.0 kJ/mol.
atomic weight of iron = 56
69.03 g = 69.03 / 56
= 1.23268 moles
Heat released by 1.23268 moles
= 1.23268 x 826.0
= -1020.9 kJ .
12 Calculate An object has a mass of 77 kg and
an acceleration of 2.3 m/s2. Use the equation
F=
= ma to calculate the net force acting on the
object. Show your work.
Answer:
F=ma.
mass=77, acceleration=2.3.
77×2.3=177.1Newton
For an experiment, you are required to prepare a series of three solutions by diluting a cobalt(II) chloride stock solution. After making each solution, you notice that each is a different shade of pink. Which is the most concentrated?
a. the lightest pink solution you prepared
b. the darkest pink solution you prepared
c. the medium pink solution you prepared
d. the stock solution
Answer:
The stock solution
Explanation:
When preparing a series of solutions from a stock solution, the stock solution will always be the most concentrated solution of the set. Each of the subsequent solutions are prepared by dilution, which entails adding solvent to a portion of the stock solution. This will always result in a solution that is less concentrated than the stock solution.
2.Which of the following compounds when dissolved in water will turn blue litmus paper red? copper oxide, calcium oxide, sulphur oxide, sodium oxide, iron oxide
Answer:
Sulphur oxide
Explanation:
All of the above oxides with the exception of sulphur oxide are basic oxides and so will not turn blue litmus paper red when dissolved in water. Sulphur oxide, SO2 on the other hand, is an acid anhydride (a non-metallic oxide which dissolves in water to produce acid) rendering it the ability of turning blue litmus paper red when dissolved in water.
Answer:sulpher oxide
Explanation:
All of the compounds except sulpher dioxide are metallic oxide which means basic oxide and base change red litmus paper to blue while acid change blue to red so the answer is the acidic oxide or sulpher dioxide
What is the MSDS? Why is it important? *
Answer:
Hey there!
A MSDS is a Material Safety Data Sheet, and can be used to provide detailed and comprehensive information about the hazards of a certain product, such as medicine or chemicals.
Let me know if this helps :)
Which of the following questions can be answered by science?
a
What is the composition of air?
b
Should the driving age be reduced?
c
What is the purpose of our existence on Earth?
d
Should students be allowed to bring toys to school?
Answer:
(a), (b) and (c) I guessAnswer:
A. What is the composition of air?, B. Should the driving age be reduced?, D.
Should students be allowed to bring toys to school? Answer: A,B,D.
Which of the following equations best describes the energy at point C.
assuming energy is conserved?
OA. PEA = KEC
O B. PEA = KEc+PEC
OC. PER = KEc+ PEC
OD. PEB = PEC
Answer:
B. PEA = KEC. +PEC
Explanation:
From the figure it is clear that there is interconversion between potential energy ( PE ) and kinetic energy ( KE ) , so that total mechanical energy is conserved .
At A only potential energy exists . Kinetic energy is zero .
At B only kinetic energy exists . Potential energy is zero .
At C both potential and kinetic energy exist .
So Potential energy at A is equal to potential energy at C and kinetic energy at C
Ie , PEA = KEC + PEC .
Option B is correct .
What is the formal thought process of science?
Answer:
In science, you are looking for something and you discovered something else. This leads to many discovery among the world.
explain formation of covalent bonds when atoms share electrons.
Answer:
Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability.
Explanation:
Find the density of a substance that’s had a volume of 24.7mL and a mass of 49.1g. Give the answer with two decimals.
Answer:
1.99 g/mL
Explanation:
Use the formula d = m/v, where m is the mass and v is the volume.
Plug in the values:
d = 49.1/24.7
d = 1.99 g/mL
Answer:
About 1.99 g/mL
Explanation:
The density of a substance can be found using the following formula:
d= m/v
where m is the mass and v is the volume.
The mass of this substance is 49.1 grams and the volume is 24.7 milliliters.
m= 49.1 g
v= 24.7 mL
Substitute these values into the formula.
d= 49.1 g / 24.7 mL
Divide 49.1 g by 24.7 mL
d= 1.98785425 g/mL
We are asked to round to two decimal places, or the hundredth place. The 8 in the thousandth place tells us to round the 8 to a 9 in the hundredth place.
d ≈ 1.99 g/mL
The density of the this substance is approximately 1.99 grams per milliliter.
Sugar when dissolved into water, propose whether the compound forms atoms, molecules or lattices. Justify you answer
Answer:
atoms
Explanation:
for sugar to dissolve in water hydaration must be equal to or greater than the lattice energy or molecular forces so when the molecular forces breaks new atoms are formed for recombination in new compound
Why the bromine and air can mix together?
A. Bromine is denser than air
B. Bromine is lighter than air
C. Bromine molecules moved upwards and molecules in air moved downwards
D. Molecules in bromine and air moved randomly
Chooses the correct statement from the above
Answer:
D. Molecules in bromine and air moved randomly
Explanation:
The molecules of both bromine and air are in the gas phase.
Since the molecules of gases are far apart and moving randomly, the bromine and air molecules can easily mix together.
A is partially correct. bromine is denser than air, but that doesn't explain why they mix.
B is wrong. Bromine is denser than air.
C is partially correct. The molecules of bromine and air moved upwards and downwards, but the also moved randomly in many other directions.
what instrument should we use if we had to carry out a small reaction
Answer:
This question appears incomplete
Explanation:
However, a glassware/instrument that is used to carry out small reactions is a beaker. It is a cylindrical instrument usually made of glass (so as not to take part in the reaction). It can also be put over a bunsen burner to heat up its content in the process of a chemical reaction. It is quite ideal for small reactions.