Answer: We see constellations at different times of the year - spring, summer, fall, & winter. This occurs because the Earth is orbiting the Sun.
Explanation:
ecology is the study of what
Answer:
Relative organisms
Explanation:
Ecology is a branch of biology that deals with the relations of organisms to one another and to their physical surroundings and conditions.
hope this helps:)
What contains more hydrogen atoms, 1.0 mole of H20 or 1.0 moles of НЗО?
H20
H30
both are equal
cannot be determined
(please show ur work)
Mercury is the only metal that is a liquid at room temperature. When mercury vapor is inhaled, it is readily absorbed by the lungs, causing signifiant health risks. The enthalpy of vaporization of mercury is 59.1 kJ/mol. The normal boiling point of mercury is 357°C. What is the vapor pressure of mercury at 43°C? Assume the enthalpy of vaporization does not depend on temperature.
Answer:
P = 0.0166 mm Hg
Explanation:
To solve this question, we need to use the Clausius Clapeyron equation, which is a commonly used expression to calculate vapour pressure at a given temperature. We have the enthalpy of vaporization of the mercury, so, let's write the equation:
Clausius Clapeyron equation:
Ln (P₂ / P₁) = (-ΔHv / R)(1/T₂ - 1/T₁) (1)
Where:
R: universal constant of gases (8.314 J / K.mol)
P₂: Vapour pressure at 43°C (or 316 K)
P₁: Pressure of mercury at the boiling point (1 atm)
T₂: temperature at 43 °C
T₁: Boiling point of mercury (357 °C or 630 K)
As we are given the boiling point of the mercury, we can safely assume that the pressure at this point is 1 atm, becuase remember that when a sustance boils, is because it's internal pressure has reached the atmospherical pressure of 1 atm. With this clear, all we just need to do is solve for P₂. We are going to do this very slowly so you can understand the process. First let's replace the given data:
Ln (P₂ / 1) = (-59100 J/mol / 8.314 J / K.mol) (1/316 - 1/630)
Ln P₂ = -7108.49 * (3.16x10⁻³ - 1.59x10⁻³)
Ln P₂ = -7108.49 * (1.51x10⁻³)
Ln P₂ = -10.7338
P₂ = 10⁽⁻¹⁰°⁷³³⁸⁾
P₂ = 2.18x10⁻⁵ atm
We can express this value in mm Hg and it will be:
P₂ = 2.18x10⁻⁵ * 760
P₂ = 0.0166 mm HgHope this helps
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What are essential elements in plants?
Answer:
Chlorophyll is one. I can't quite remember other
14.86 ml + 15.0 ml + 14.980 ml =
Answer:
44.84 ml
Explanation:
14.86
+
15.0
+
14.980
_______
44.84
What does "X" represent in the following symbol?
80
Х
35
Answer:bromine
Explanation:
Help ASAP please
Which statement best describes the reaction pathway graph for an exothermic reaction but not an endothermic reaction?
It has a hill in the middle that is the highest point.
It has a valley in the middle that is its lowest point.
The reactants are higher in energy than the products.
The products are higher in energy than the reactants.
Answer: C ) The reactants are higher in energy than the products
Explanation:
The enthalpy that is a state variable that identifies the content of heat. Then the change of enthalpy for the exothermic reactions is negative, meaning that the energy of the products is lower than the energy of the reactants.
I need some help to determine the mole and grams pls I would really appreciate the help
Answer:
[tex]n_{FeS}=0.686molFeS \\\\n_{H_2S}=23.3gH_2S[/tex]
Explanation:
Hello!
In this case, according to the given chemical reaction, it is possible to apply the following stoichiometric setups in order to compute the moles of reacting FeS and the grams of produced H2S, given the mass of HCl (molar mass = 36.46 g/mol) as shown below:
[tex]n_{FeS}=50.0gHCl*\frac{1molHCl}{36.46gHCl}*\frac{1molFeS}{2molHCl}\\\\n_{FeS}=0.686molFeS \\\\\\m_{H_2S}=50.0gHCl*\frac{1molHCl}{36.46gHCl}*\frac{1molH_2S}{2molHCl}*\frac{34.04gH_2S}{1molH_2S} \\\\n_{H_2S}=23.3gH_2S[/tex]
Best regards!
please help. it’s my last question.
Given
Atomic symbol
Required
Atomic composition
Solution
Atomic number = number of protons = number of electrons
Mass Number (A) is the sum of protons and neutrons
Number of protons and Number of Neutrons in nucleus
Number of electrons in the shell
From the picture:
protons = 3
neutrons = 4
electrons = 3
atomic number = protons = electrons = 3
mass number = protons + neutrons = 3+4 = 7
Convert 3.93 x 10-22 grams of X4Z3 into molecules/formula units of the same compound. (Assume that the molar mass of X is 59.45 grams per mole and the molar mass of Z is 13.84 grams per mole.)
Assume that Avogadro's number is 6.022 x 1023. Report your answer to three decimal places.
Answer:
0.847 molecule.
Explanation:
From the question given above, the following data were obtained:
Mass of X₄Z₃ = 3.93×10¯²² g
Number of molecules of X₄Z₃ =?
Avogadro's number = 6.022×10²³ molecules
Next, we shall determine the molar mass of X₄Z₃. This can be obtained as follow:
Molar mass of X₄Z₃ = (4×59.45) + (3×13.84)
= 237.8 + 41.52
= 279.32 g/mol
Finally, we shall determine the number of molecules in 3.93×10¯²² g of X₄Z₃. This can be obtained as follow:
From Avogadro's hypothesis,
1 mole of X₄Z₃ = 6.022×10²³ molecules
But 1 mole of X₄Z₃ = 279.32 g
Thus we can say that:
279.32 g = 6.022×10²³ molecules
Therefore,
3.93×10¯²² g = 3.93×10¯²² × 6.022×10²³ / 279.32
3.93×10¯²² g = 0.847 molecule.
Thus, 3.93×10¯²² g of X₄Z₃ contains 0.847 molecule.
(1) Solution A and B are separated by a membrane that is permeable to Mg2 and impermeable to Cl-. Solution A contains 0.1 mM MgCl2, solution B contains 100 mM MgCl2. Mg2 will be at electrochemical equilibrium when solution A is around ____________ mV. 180 mV - 180 mV 90 mV - 90 mV 60 mV - 60 mV
Answer:
90 mV
Explanation:
Faraday constant, F = 96487
Gas constant, R = 8.314
Number of mole of electron transferred, Z = 2
MgCl in solution A, = 0.1 mm
MgCl in solution A, = 100 mm
Using the relation :
E=(RT/ZF) In(Mg out/Mgin)
E = (8.314*298) / (2*96485) * In(100/0.1)
E = (2477.572 / 192970) * 6.9077552
E = 0.0128391 * 6.9077552
E = 0.0886897 V
E = 88.68 mV (approximately 90 mV)
According to the following reaction, how many moles of calcium chloride will be formed upon the complete reaction of 27.9 grams of calcium hydroxide with excess hydrochloric acid? calcium hydroxide (aq) + hydrochloric acid (aq) calcium chloride (aq) + water (l) moles calcium chloride
Answer: 0.377 moles of calcium chloride will be formed.
Explanation:
To calculate the moles :
[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]
[tex]\text{Moles of} Ca(OH)_2=\frac{27.9g}{74g/mol}=0.377moles[/tex]
The balanced chemical reaction is:
[tex]Ca(OH)_2+2HCl\rightarrow CaCl_2+2H_2O[/tex]
According to stoichiometry :
As 1 mole of [tex]Ca(OH)_2[/tex] give = 1 mole of [tex]CaCl_2[/tex]
Thus 0.377 moles of [tex]Ca(OH)_2[/tex] give =[tex]\frac{1}{1}\times 0.377=0.377moles[/tex] of [tex]CaCl_2[/tex]
Thus 0.377 moles of calcium chloride will be formed upon the complete reaction of 27.9 grams of calcium hydroxide with excess hydrochloric acid
This is to be removed in brown sugar and to be rolled with a rolling pin?
Answer:
The lumps should be removed in brown sugar and to be rolled with rolling pin.
Explanation:
In preparing brown sugar as ingredients in baking and pastry, it is important to check if the sugar is lumpy. Although it is not the main ingredient in baking, it is important to check because it could affect the texture of the mixtures. Brown sugar is also much nutritious to white sugar that is why it is more commonly use. The brown sugar become lumpy because when brown sugar is exposed to air it gets harder because the molasses that keeps its soft evaporates that makes the sugar stick together. The rolling pin helps the lump to break up.
How to get the density of this unknown liquid?
Answer:
Measure the volume of water poured into a graduated cylinder, then place the object in the water and remeasure the volume. The difference between the two volume measurements is the volume of the object. Now simply divide the mass by the volume to calculate the density of the object.
Which individual elements make up the following common
compounds?
CaCO 3
CaCl 2
C H O 3 6
HCl
Ca(OH) 2
Answer:
I think it will carbon hope it helps
How many moles are in 3.01 x 10^23 atoms of zinc?
Answer:
What is ^ for?
Explanation:
You are working to earn enough money for a vacation which costs 2100. Your take-home pay is $16.50/hour, but you only work 4-hour shifts each day. How many days will it take for you to earn enough money to pay for your vacation if all the money you earn goes towards your vacation?
Answer:
32 days.
Explanation:
First we determine how much is made in a day.
16.50 x 4 = 66.
Next, we divide 2100 by 66 to reach our amount of days needed.
2100 / 66 = 31.818181... [81 is what repeats over and over.]
We round this up to the nearest whole number. You can't underpay, so you have to round.
The next whole number would be 32, so our answer is 32 days.
Question 12 (1 point)
You notice light pollution in
a.space
b.big cities
c.rural areas
d.our galaxy
Answer:
the answer is D . our galaxy
Answer:
our galaxy of course
Examine the diagram of the cell cycle. Which label identifies the stage in which the DNA is copied and the cell grows? W X Y Z
Explanation:
w is the stage in which dna is copied and cell grows.
Answer:
w
Explanation:
PLEASE HURRY ILL GIVE 95 POINTS!
A student dissolved 5g of table salt in 100 mL of water in a beaker. When you compare the total mass of the salt and water before mixing to the mass of the solution after mixing, which is true?
A. The total mass of the solution after mixing, Will increase by a large amount
B. The total mass of the solution after mixing, Will increase by a small amount
C. The total mass of the solution after mixing will neither increase nor decrease
D. The total mass of the solution after mixing, Will decrease by a small amount
Answer:
B.
Explanation:
Answer:
B is the correct answer
Explanation:
David Robinson, a professional basketball
player, is 7 ft, 1.0 in. tall. Convert his height to
centimeters
Show work please
Answer:
215.9 cm
Explanation:
1 foot= 30.5cm
30.5cm times 7 1/12=215.9cm
The given height of David is 7 ft, 1.0 inch, so in centimeters, the height will be 216.4 cm.
What is unit conversion?A conversion factor is a number that is used to multiply or divide one set of units into another. When converting to an equal value, the appropriate conversion factor must be used.
We must convert one unit to another in order to achieve accuracy and avoid measurement confusion.
We do not, for example, measure the length of a pencil in kilometers. In this case, one must convert kilometers (km) to centimeters (cm) (cm).
To convert feet to centimeters, multiply the given foot length by 30.48 cm.
So,
Height in cm will be = 7.1 x 30.48
Height in cm = 216.4cm
Thus, the height of David in centimeters is 216.4 cm.
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ANSWER ASAP
2. The figure shows the first three rows, or periods, of the periodic table. Suppose the fourth period is added. How many orbits will the Bohr models in the fourth period have? How many electrons will an atom in Group 1 in the fourth period have?
Answer:
4 orbits in the fourth period.
19 electrons in the atom from group 1 and fourth period.
Explanation:
Potassium has 19 electrons distributed in its 4 orbits
The number of periods in a periodic table, tells the number of shells or orbitals of the atoms in that row in which the electrons are filled. Thus the fourth period elements have 4 orbitals and the first element in group one of the fourth period is potassium containing 19 electrons.
What are periods in periodic table?All elements in a periodic table are classified into different groups and periods. The vertical columns in the periodic table is called groups and the horizontal rows are called periods.
A group contains elements with same number of valence electrons and similar physical and chemical properties. In a period from left to right the atomic number increases but the number of orbitals in which the electrons are filled will be the same.
Down a group the number of orbitals increases by one. Thus, each elements contains electrons in an increment of 8, 18, 18 and 32 down a group. Thus, from third period to fourth period the number of orbital increases to 4.
The number of electrons will be +8 from the previous element in the group in third period. Thus, below sodium (11) the first element in fourth period is potassium with 19 electrons.
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Determine the density (in g/mL) of a substance with a mass of 105 g and a volume of 17.6 mL.
Answer:
Density, d = 5.96 g/mL
Explanation:
Given that,
Mass, m = 105 g
Volume, V = 17.6 mL
We need to find the density of the substance. So,
[tex]d=\dfrac{m}{V}\\\\d=\dfrac{105\ g}{17.6\ mL}\\\\d=5.96\ g/mL[/tex]
So, the density of the substance is 5.96 g/mL.
PLEASE HELP this is physical science.
Bone age : 22,920 years
Further explanationGiven
Nt = 2.5 g C-14
No = 40 g
half-life = 5730 years
Required
time of decay
Solution
General formulas used in decay:
[tex]\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}[/tex]
t = duration of decay
t 1/2 = half-life
N₀ = the number of initial radioactive atoms
Nt = the number of radioactive atoms left after decaying during T time
Input the value :
[tex]\tt 2.5=40.\dfrac{1}{2}^{t/5730}\\\\\dfrac{2.5}{40}=\dfrac{1}{2}^{t/5730}\\\\(\dfrac{1}{2})^4=\dfrac{1}{2}^{t/5730}\\\\4=t/5730\rightarrow t=22920~years[/tex]
How many carbon atoms are represented by Mg(HCO3)
Here is the reaction of carbamic acid and ammonia to form an amide and water. There is a scheme of a reversible reaction where carbamic acid reacts with ammonia to give water and an unknown compound. Carbamic acid is H2NCOH with an oxygen atom attached to the carbon atom by a double bond. Ammonia is a nitrogen atom with three H atoms attached. Water is HOH. Draw the amide product of this reaction.
Answer:
See explanation
Explanation:
I have attempted to show the sequence of the reaction between carbamic acid and ammonia to form an amide and water and urea.
The reaction first involves the protonation of ammonia to give ammonium carbamate.
When ammonium carbamate is heated to 130-140 degrees, we obtain urea and water as the final products of the reaction
what is this for questions 2
Answer:
I think is D
Explanation:
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which changes when gases condense to form liquids
In condensation, matter changes from a gas to a liquid. All matter is made of tiny moving particles called molecules. Evaporation and condensation happen when these molecules gain or lose energy. This energy exists in the form of heat.
What is the name of the process happening in the picture? How do you know it’s that process? Explain your answer in 2 to 3 complete sentences