What is the molality of a solution containing 18.2 g HCl and 250. g of water?
Answer:
m=2.0mol/kg
Explanation:
Hello there!
In this case, according to the formula to compute molality, which requires moles of solute (HCl) and kilograms of solvent (water), we first compute the moles of the former with its molar mass as shown below:
[tex]n=\frac{18.2g}{36.46g/mol}= 0.50mol[/tex]
And then the kilograms of water:
[tex]\frac{250.g}{1000g/kg} =0.250kg[/tex]
Finally, the molality turns out to be:
[tex]m=\frac{0.50mol}{0.250kg}\\\\m=2.0mol/kg[/tex]
Best regards!
Uranium, an important component of both nuclear weapons and nuclearreactors, has two major isotopes, U-238, which has a half-life of approximately billion years, and U-235, which has a half-life of approximately million years. Both were present in equal amounts at the time of thecreation of the Earth, billion years ago. How many years after the creationof the Earth had the amount of radiation from uranium decayed to half theamount present at the time of the creation of the Earth
Answer:
Hello your question is poorly written below is the well written question
Uranium, an important component of both nuclear weapons and nuclear reactors, has two major isotopes, U-238, which has a half-life of approximately 4.5 billion years, and U-235, which has a half-life of approximately 700 million years. Both were present in equal amounts at the time of the creation of the Earth, 4.5 billion years ago. How many years after the creation of the Earth had the amount of radiation from uranium decayed to half the amount present at the time of the creation of the Earth
Answer : 140 billion years
Explanation:
Given that :
U-238 h1/2 = 4.5 billion years
U-235 h1/2 = 700 million years
At the beginning both Isotopes where present in equal amount
Determine the T years before the amount of Uranium decays to Half
T = ? N'2 = N1 / 2
we know that N = No ( 1/2 )^h where h = time / half-life time
attached below is the detailed solution of the given problem
How many Protons, Electrons and Neutrons does Helium-6 have?
Answer:
12 neutrons
2 protons
2 electrons
Answer:
Hello There!!
Explanation:
Helium 6 has:
-two protons
-two electrons
-two neutrons
hope this helps,have a great day!!
~Pinky~
Solubility is the mass in a given volume of a substance.
True
False
Answer: True
Explanation:
Calculate the pH at the equivalence point when 22.0 mL of 0.200 M hydroxylamine, HONH2, is titrated with 0.15 M HCl. (Kb for HONH2
Answer:
pH = 3.513
Explanation:
Hello there!
In this case, since this titration is carried out via the following neutralization reaction:
[tex]HONH_2+HCl\rightarrow HONH_3^+Cl^-[/tex]
We can see the 1:1 mole ratio of the acid to the base and also to the resulting acidic salt as it comes from the strong HCl and the weak hydroxylamine. Thus, we first compute the required volume of HCl as shown below:
[tex]V_{HCl}=\frac{22.0mL*0.200M}{0.15M}=29.3mL[/tex]
Now, we can see that the moles of acid, base and acidic salt are all:
[tex]0.0220L*0.200mol/L=0.0044mol[/tex]
And therefore the concentration of the salt at the equivalence point is:
[tex][HONH_3^+Cl^-]=\frac{0.0044mol}{0.022L+0.0293L} =0.0858M[/tex]
Next, for the calculation of the pH, we need to write the ionization of the weak part of the salt as it is able to form some hydroxylamine as it is the weak base:
[tex]HONH_3^++H_2O\rightleftharpoons H_3O^++HONH_2[/tex]
Whereas the equilibrium expression is:
[tex]Ka=\frac{[H_3O^+][HONH_2]}{[HONH_3^+]}[/tex]
Whereas Ka is computed by considering Kw and Kb of hydroxylamine:
[tex]Ka=\frac{Kw}{Kb}=\frac{1x10^{-14}}{9.10x10^{-9}} \\\\Ka=1.10x10^{-6}[/tex]
So we can write:
[tex]1.10x10^{-6}=\frac{x^2}{0.0858-x}[/tex]
And neglect the x on bottom to obtain:
[tex]1.10x10^{-6}=\frac{x^2}{0.0858}\\\\x=\sqrt{1.10x10^{-6}*0.0858}=3.07x10^{-4}M[/tex]
And since x=[H3O+] we obtain the following pH:
[tex]pH=-log(3.07x10^{-4})\\\\pH=3.513[/tex]
Regards!
3.0L of a gas is at a temperature of 78c. Find the volume of the gas at standard temperature
Answer:
V=2.33361811192L or 2.3x10
Explanation:
Using Charles law V1/T1=V2/T2 Remember to convert celcius to kelvin by using the standard temperature 273.15K
3L/(78C+273.15)=V/273.15
In this field of sunflowers variation exists some flowers are tall others short
Answer:
Some flowers are tall, others short, and finally some plants are an intermediate height. The tallest plants shade the shorter; the taller plants are
Explanation:
pleaaaaase helppppppppppppp ASAP
Answer:
Explanation:
a) The forward reaction is exothermic, hence when temperature is increased the equilibrium shift towards the reactants side to get rid of the excess energy. This will mean that more reactants are produced decreasing yield
b) There are a fewer number of moles of gas on the right side compared to the left side (Just count the coefficients before each compound) so a higher pressure will mean that the equilibrium will shift towards the products side in order to decrease the pressure. This will mean that more products are formed increasing yield
c) When something is powdered it's surface area to volume ratio increases. A higher surface area means that the particles around it have more area to work on so the frequency of collisions will increase increasing the rate of reaction. This is why iron is powdered.
A hot metal plate at 150°C has been placed in air at room temperature. Which event would most likely take place over the next few minutes?
Molecules in both the metal and the surrounding air will start moving at lower speeds.
Molecules in both the metal and the surrounding air will start moving at higher speeds.
The air molecules that are surrounding the metal will slow down, and the molecules in the metal will speed up.
The air molecules that are surrounding the metal will speed up, and the molecules in the metal will slow down.
Answer:
The air molecules that are surrounding the metal will speed up, and the molecules in the metal will slow down.
Explanation:
There will be a transfer of thermal energy (heat) from the hot metal plate to the surrounding air. This transfer of energy equates to a transfer of kinetic energy in the molecules. As the plate loses heat, the molecules in the plate will lose kinetic energy and slow down. As the surrounding air gains heat, the molecules will gain kinetic energy and speed up.
Answer: C
Explanation:
How can you determine if elements have the same properties?
Answer:
You will know if elements have the same properties if they are in the same column (up and down) on the periodic table.
Explanation:
Ex: Lithium and a hydrogren has the same properites bcause they are both on the same line/column. Columns are up and down the table and rows are left and right. Hope this helps
Solution remained colorless.
During the experimentation, the test tube was gently heated in a Bunsen burner flame for 60 seconds. What was the reason for this specific
procedure?
A)
Heating was done to initiate the combustion of the metal in water.
B)
Heating was done to confirm that no chemical reaction would take
place in acid
0
Heating was done to precipitate the chemical change in each test
tube containing water
D)
Heating helped released the hydrogen contained in water
molecules so students would have a positive H+ test.
what makes up the cell menbrane
With few exceptions, cellular membranes — including plasma membranes and internal membranes — are made of glycerophospholipids, molecules composed of glycerol, a phosphate group, and two fatty acid chains. Glycerol is a three-carbon molecule that functions as the backbone of these membrane lipids.
Explanation:
the principal components of plasma membrane are lipids phospholipid and cholesterol proteins and carbohydrates
What is the pressure exerted by 2.5 mol of gas with a temperature of 25 Celsius and a volume of 12.2 L
Answer:
5.01 atm
Explanation:
To answer this question, we're going to use the PV=nRT equation, where in this case:
P = ?V = 12.2 Ln = 2.5 molR = 0.082 atm·L·mol⁻¹·K⁻¹T = 25 °C ⇒ 25 + 273.16 = 298.16 KWe input the data:
P * 12.2 L = 2.5 mol * 0.082 atm·L·mol⁻¹·K⁻¹ * 298.16 KAnd finally solve for P:
P = 5.01 atmA chunk of zinc is added to a solution of gold (III) nitrate to extract the gold. The reaction forms,
zinc nitrate and the precipitate gold.
Explanation:
Gold (AU)................
Identify the type of reaction.
Al + MgSO4 = Al2(SO4)3 + Mg
Answer: its combustion
Explanation:
calculate the ph of one solution containing 0.1 M formic acid and 0.1 M sodium formate before and after the addition of 1mL of 5 M Naoh. how much could the Ph change if the NaOh were added to 1 L of pure water
Answer:
Pka of formic acid (HCOOH)= 3.75
pH= PKa +log [ Sodium formate/ formic acid] = 3.75
NaOH reacts with HCOOH as HCOOH (aq) + NaOH(aq) --> NaCHO2 (aq) and H2O (l)
Moles of HCOOH= 0.1*1= 0.1 moles
Moles of NaOH= 5*1/1000= 0.005 moles
HCOOH is in excess and the excess is = 0.1 - 0.005 = 0.095
Moles of sodium formate = 0.005 + 0.1 = 0.105 moles of HCOOH= 0.095
volume after mixing = 1 + 5 /1 000=1.005
Concentrations : HCOOH= 0.095/1.005 sodium formate= 0.105/1.005
pH= 3.75+log (0.105/0.095)=3.85
When NaOH is added, molarity is , 1*5= 1000*M
M= 5/1000=0.005
The pH remains the same. Only the molarity of NaOH changes.
How many calcium atoms are in 56.5 g of calcium?
Answer:
there are 8.501×10^23 atoms of Ca atoms
The diagrams below show the alignment of the Sun, the Moon, and Earth.
Answer:A
Explanation: I learned it from a gizmo
is oxygen a beginning substance or ending substance?
write the value of atmosphere pressure at sea level .
Answer:
standard sea- level pressure,by definition,equals 760 mm of Mercury,14.70 pounds per square inch, 1,013.25x10³ dynes per square centimetre, 1,013.25 millibars,one standard atmosphere,or 101.325 kilopascale
Here's your answerl hope it's helpful for u....
This equation shows the combustion of methanol.
2CH2OH(1) +302(g) → 2C02(g) + 4H2O(g)
How many liters of carbon dioxide gas at STP are produced by the combustion of 64.0 g of methanol
(CH3OH)
A. 44.8L
B. 89.6 L
C. 11.2L. D. 22.4L
Answer: 44.8 L
Explination:
44.8 liters of carbon dioxide gas at STP are produced by the combustion of 64.0 g of methanol. Therefore, option A is correct.
What is combustion ?Combustion is a chemical reaction between two or more substances, usually involving oxygen, that produces heat and light in the form of a flame.
Combustion is a high-temperature exothermic redox chemical reaction that occurs between a fuel and an oxidant, frequently atmospheric oxygen, to produce oxidized, often gaseous products in a mixture known as smoke.
The flash point of methanol is extremely low. This means that even trace amounts of ignition material can start a fire. 44.8 liters of carbon dioxide gas at STP are produced by the combustion of 64.0 g of methanol.
Thus, option A is correct.
To learn more about the combustion, follow the link;
https://brainly.com/question/15117038
#SPJ6
Which if the following numbers in your personal life are exact numbers?
A. Your cell phone number
B. Your weight
C. Your IQ
D. Your driver's license number
E. The distance you walked yesterday
Answer:
I think D
Explanation:
Your cell phone number and your driver's license number are the numbers of your personal life that are exact.
In this context, an exact number refers to a number that if it undergoes any modification will not refer to the same thing that it referred to before that modification.
For example, my phone number is 12345. This number is exact because it cannot be changed because or else it would cease to be my phone number, that is, if someone wants to call me and writes the number 12346 it is no longer my number.
Addicionally, if my driver's license number is 112233 it is an exact number because if it is modified it would be the number of another driver.
According to the above, options B, C, and E are incorrect because they are inaccurate numbers because if they are modified they all refer to me and they would not change their meaning.
Learn more in: https://brainly.com/question/17093923
what happens when ?? Fresh red flower is introduced into a vessel contain Sulphur dioxide along
with moisture.
7x[(7+7)divide7]
PLEASE HELP
Answer:
ik this isnt the answer but mathwa will solve all yours problems
Explanation:
how proved that carbon is present in sugar?
In all living organisms, in substances like carbohydrate, starch, urea etc. To prove sugar contains carbon, take a little amount of sugar in spoon and heat it gently till it melts and turned into yellowish color. On further heating it changes into brown colored mass and then black, which is charcoal.
Answer: sugar treated with strong sulphur acid turns to black
Explanation: sulphur acid removes water from sugars and carbon is left in residue.
This should not to try at home. Water boils when high temperature is achieved.
Also smell of burned sugar occurs
5. What types of surfaces would result in greater friction?
Answer:
Rough and irregular surface
these surfaces tends a lot of friction
but on smooth surface there is least friction
hope it helps
Estimate the crystal field stabilization energy for the octahedral ion hexacyanomanganate(III) , if the wavelength of maximum absorption for the ion is 600 nm. [Note: This is a high-field (low-spin) complex.]
Answer:
The crystal field stabilization energy for the octahedral ion hexacyanomanganate(III) , if the wavelength of maximum absorption for the ion is 600 nm is - 1987.59kJ/mole
Explanation:
Lets calculate -:
Crystal field stabilization energy -
[tex]E=\frac{hc}{\pi }[/tex]
where h = planks constant = [tex]6.626\times10^-^3^4 Js[/tex]
c= velocity of light = [tex]3\times10^8m/second[/tex]
[tex]\pi =wavelength=600nm=600\times10^-^9m[/tex]
[tex]E=\frac{6.626\times10^-^3^4\times3\times10^8}{600\times10^-^9}[/tex]
=[tex]0.033\times10^-^1^6 J/ion[/tex]
= [tex]0.033\times10^-^1^6\times6.023\times10^2^3[/tex]
= [tex]0.198759\times10^7 J/mole[/tex] = [tex]1987.59\times10^3J/mole[/tex]
= [tex]1987.59kJ/mole[/tex]
Thus , the crystal field stabilization energy for the octahedral ion hexacyanomanganate(III) is 1987.59kJ/mole
HELP FAST 100 PTS Calculate the amount of heat needed to lower the temperature of 50.0g of ice from -40 °C to -100 °C.
Answer:
[tex]\Large \boxed{\sf -6000 \ J}[/tex]
Explanation:
Use formula
[tex]\displaystyle \sf Heat \ (J)=mass \ (kg) \times specific \ heat \ capacity \ (Jkg^{-1}\°C^{-1}) \times change \ in \ temperature \ (\°C)[/tex]
Specific heat capacity of ice is 2,000 J/(kg °C)
Substitute the values in formula and evaluate
[tex]\displaystyle \sf Heat \ (J)=0.05 \ kg \times 2000 \ Jkg^{-1}\°C^{-1} \times (-100\°C-(-40 \°C))[/tex]
[tex]Q=0.05 \times 2000 \times (-100-(-40)) =-6000[/tex]
A sample of carbon dioxide gas at a pressure of 686 mm Hg and a temperature of 73 C, occupies a volume of 6.34 liters. If the gas is cooled at constant pressure to a temperature of 35 C, the volume of the gas sample will be ____________ L.
Recall the ideal gas law,
P V = n R T
Find the amount of CO₂ in the sample, n :
P = 686 mm Hg ≈ 91,459 Pa
V = 6.34 L
R = 8.3145 J/(mol•°K)
T = 73 °C = 346.2 °K
→ n = P V / (R T ) ≈ 0.20147 mol
Now find the volume V of the sample when the temperature T is 35 °C = 308.2 °K :
V = n R T / P ≈ 5.6349 L ≈ 5.63 L
What is the mass percent of potassium sulfate in solution if 78g of potassium sulfate is dissolved in 500 mL of water? (The density of water is 1.00 g/mL)
Answer:
13.5 %
Explanation:
First we calculate the mass of 500 mL of water, using its density:
Volume * Density = Mass500 mL * 1.00 g/mL = 500 gThen we calculate the mass percent of potassium sulfate, using the formula:
Mass of Potassium Sulfate / Total Mass * 100%
78 g / (78 + 500) g * 100 % = 13.5 %