Answer:
2.48x10¹³ miles is the distance from the earth to Proxima Centauri
Explanation:
Light years is an unit of distance used in Astronomy. That is because 1 light year = 9.461x10¹²km; a real big distance used in the science that study the universe.
In km, 4.22 light years are:
4.22 light years * (9.461x10¹²km / 1 light year) = 3.9925x10¹³km
As 1 mile = 1.60934km, this distance in miles is:
3.9925x10¹³km * (1 mile / 1.60934km) =
2.48x10¹³ miles is the distance from the earth to Proxima Centauri200ml hard water was boiled with 100ml N/50 Na2CO3 reagent. After boilingg the volume was again made to 200mand the solution filtered. 25ml of this filtrate required 8.2ml of N/50 HCl for neutralisation
Answer:
Here is the full question:
200ml hard water was boiled with 100ml N/50 Na2CO3 reagent. After boilingg the volume was again made to 200mand the solution filtered. 25ml of this filtrate required 8.2ml of N/50 HCl for neutralisation.
Calculate the permanent hardness in ppm.
Explanation:
Remember that the hard water was boiled with 100ml N/50 Na2CO3 reagent. Therefore, the milliequivalent of carbonate ion in 100 ml of N/50 Na2CO3 solution is given as 100 × [tex]\frac{1}{50}[/tex] = 2
The solution was made of 200 ml and 25 ml of the filtrate was neutralised with 8.2 ml N/50 HCl.
The milliequivalent of carbonate ions remaining in the filtrate is [tex]\frac{200}{25}[/tex] × 8.2 × [tex]\frac{1}{50}[/tex] = 1.3 milliequivalent
To get the milliequivalent of carbonate ion precipitated, we need to subtract the milliequivalent of the two carbonate ions. This will give us
2 − 1.3 = 0.7g
The amount of CaCO3 present in 200 ml water = 0.7 × 50 = 35g
Permanent hardness = [tex]\frac{35}{200}[/tex] × 1000 = 175 ppm.
Permanent hardness of water after boiling is 175ppm.
What is hardness of water?Hardness of water is of two types, one those will cam be removed by boiling is known as temporary hardness and which can not be removed by boiling is known as permanent hardness.
Given that hard water is heated with = 100mL N/50 Na₂CO₃.
Milliequivalent of carbonate ion in 100ml of N/50 Na₂CO₃ = 100×1/50=2
The milliequivalent of carbonate ions remaining in the filtrate is 200/25× 8.2 × 1/50 = 1.3 milliequivalent
Milliequivalent of carbonate ion precipitated = 2 - 1.3 = 0.7g
The amount of CaCO₃ present in 200 ml water = 0.7 × 50 = 35g
Permanent hardness will be calculated as:
P.H. = 35/200 × 1000 = 175ppm.
Hence, permanent hardness of water is 175ppm.
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What is the molecular formula and chemical name of the compound? Examine the image. The letters Si in the center with four lines connecting it to 4 Fs, 1 in each direction.
Answer:
molecular formula is "SiF4" and compound name is "silicon tetrafluoride"
Explanation:
how can chemistry help solve a crime ?
plz helppp
Chemistry is vital in forensic science (used to solve crimes). With chemistry, forensic scientists demonstrate what happened on a molecular level. Chemical analysis can reveal how long ago a person died, what weapon was used, the kind of tape or rope used to tie someone up, etc. They also analyze drugs/controlled substances taken from scenes and people to identify and sometimes quantify these materials.
explain why the neutralization reaction of a strong base and weak acid gives a weakly basic solution
Answer:
when an acid react with a base, salt and water is produced. It is because the nature of salt formed determines whether the solution is neutral, acidic or basic
Hope this helps :)
define what is halflife
Answer: the time taken for the radioactivity of a specified isotope to fall to half its original value.
Explanation:
Answer:
Half-life is the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo, or how long stable atoms survive, radioactive decay.
For molecules with multiple ionizable groups, such as glycine, which of the following statements is true?1. At a pH near the pI, nearly all the molecules carry a net positive charge.2. At pH near the pI, nearly all the molecules carry no net charge.3. At a pH near the pI, nearly all the molecules carry a net negative charge.4. When the pH is near the pI, the solution is near its
Answer:
2. At pH near the pI, nearly all the molecules carry no net charge
Explanation:
The general equilibrium for a molecule with multiple ionizable groups could be:
H₃A⁺ ⇄ H₂A + H⁺ ⇄HA⁻ + H⁺⇄A²⁻ + H⁺
Where each equilibrium has its own pKa
The equilibriums in which H₂A are involved (The neutral molecule), are used to determine the isoelectrical point.
The isoelectrical point is defined as the value of pH in which the molecule has no net charge.
Thus, true option is:
2. At pH near the pI, nearly all the molecules carry no net chargehow many pi bonds does a triple bond has
Answer:
A triple bond have two pi bonds.
Explanation:
This is an alkaline that contains one sigma bond and two pi bonds.
Hope my answer helps.
Answer:
Two
Explanation:
Is a Animal and Plant cell living
How many L are in 0.74 CL ?
Answer:
0.0074 cL
7.4 x 10⁻³ cL
Explanation:
Step 1: Find conversion
1 liter (L) = 100 centiliters (cL)
Step 2: Set up dimensional analysis
[tex]0.74cL(\frac{1L}{100cL} )[/tex]
Step 3: Multiply and cancel out units
cL and cL cancel out.
We are left with L.
0.74/100 = 0.0074 cL or 7.4 x 10⁻³ cL
Why is a 9-v transistor battery used as the source of electrical power for electrolysis rather than the power supply that plugs into the wall electrical current?
Answer:
The 9-v transistor battery is a direct current source, while the power supply from the wall socket is an alternating current source.
Explanation:
A direct current (DC) is one that flows continuously without any minimum and maximum values. This is majorly obtained from generators, batteries or cells etc.
An alternating current (AC) is a type that flows in a sinusoidal manner, having minimum and maximum value with respect to its flowing frequency. An example is the one obtained from the wall electrical source , generators etc.
An alternating current is not mainly used for electrolysis because of its nature. It would cause a switch of the electrodes in every cycle. Therefore, a direct current source is used.
The 9-v transistor battery is a direct current source, while the power supply from the wall is an alternating current source.
Perform the calculation, rounding your answer to the proper number of significant figures.
0.8730 divided by 9.650 =
Answer:
Hey!
0.8730 / 9.650 = 8.42445
Explanation:
8.42445 TO 2 s.f... (best option for rounding)
= 8.4
ANSWER = 8.4 (2 s.f)
HOPE THIS HELPS!!
How many electrons does each lithium atom provide to the voltaic cell? Question 6 options: A) 2 B) 1 C) 3 D) 4
Answer:
B) 1
Explanation:
Lithium is a univalent element, univalent means that it has only one valence electron. If this is true, then lithium can only provide this one valence electron in a voltaic cell.
From the foregoing, each lithium atom can only provide one valence electron in the voltaic cell.
Answer:
B) 1
Explanation:
I got it in class!
Hope this Helps!! :))
A reagent bottle contains a stock solution of 0.90% by mass of sodium chloride, NaCl.
The density of the solution is 1.00 g cm ?. Calculate
(i) the mole fraction of NaCl
(ii) the molality of NaCl solution
(111) the volume of the stock solution required to prepare 100 mL of 0.01 M NaCl
solution.
Answer:
I. 2.79x10⁻³
II. 0.155m
III. 6.49mL of the solution you must add from the stock solution
Explanation:
A solution of 0.90% by mass NaCl means that, in 100g of solution, you have 0.90g of NaCl. In other words, there are 0.90g of NaCl + 99.1g of water.
I. Mole fraction of NaCl is the ratio between moles of NaCl and total moles of solution.
Moles NaCl:
0.90g * (1mol / 58.44g) = 0.0154 moles NaCl
Moles water:
99.1g water * (1mol / 18.01g) = 5.50 moles water.
Total moles = 5.50 +0.0154 moles = 5.518 moles
Mole fraction NaCl: 0.0154 / 5.518 moles =
2.79x10⁻³II. Molality is the ratio between moles of solute (NaCl) and kg of solvent.
There are 99.1g of water = 0.0991kg.
Molality is: 0.0154 moles / 0.0991kg
0.155mII. 100mL of a 0.01M are:
100mL = 0.100L * (0.01 mol / L) = 1x10⁻³ moles of NaCl
In 100g = 100mL (Density of 1g/mL) there are 0.0154 moles. To have 1x10⁻³ moles you need:
1x10⁻³ moles of NaCl * (100mL / 0.0154 moles) =
6.49mL of the solution you must add from the stock solutionI. Mole fraction of NaCl is 2.79x10⁻³
II. Molarity of NaCl solution is 0.155m
III. 6.49mL of the stock solution required to prepare 100 mL of 0.01 M NaCl solution.
What does % by mass mean?
A solution of 0.90% by mass NaCl means that, in 100g of solution, you have 0.90g of NaCl.
Or
There is 0.90g of NaCl + 99.1g of water.
We need to find:
I. Mole fraction of NaCl:
Mole fraction can is the ratio of moles of Solute to the total number of moles of the solutes and the solvent.
Moles of NaCl(solute) = 0.90g * (1mol / 58.44g) = 0.0154 moles NaCl
Moles of water(solvent) = 99.1g water * (1mol / 18.01g) = 5.50 moles water.
Total moles = 5.50 +0.0154 moles = 5.518 moles
Mole fraction of NaCl = [tex]\frac{0.0154}{ 5.518} =2.79 * 10^{-3}[/tex]
II. Molality is a measure of the number of moles of solute(NaCl) in a solution corresponding to 1 kg or 1000 g of solvent
Since, 99.1g of water = 0.0991kg.
Molality of NaCl = [tex]\frac{0.0154 moles}{0.0991 kg}=0.155m[/tex]
III. 100mL of a 0.01M is:
100mL = 0.100L * (0.01 mol / L) = 1x10⁻³ moles of NaCl
In 100g = 100mL (Density of 1g/mL) there are 0.0154 moles. To have 1x10⁻³ moles you need:
1x10⁻³ moles of NaCl * [tex]\frac{100 mL}{0.0154 moles}[/tex] = 6.49mL of the solution you must add from the stock solution
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After mixing an excess PbCl2 with a fixed amount of water, it is found that the equilibrium concentration of Pb2 is
Answer:
Ksp = 8.8x10⁻⁵
Explanation:
Full question is:
After mixing an excess PbCl2 with a fixed amount of water, it is found that the equilibrium concentration of Pb2+ is 2.8 × 10–2 M. What is Ksp for PbCl2?
When an excess of PbCl₂ is added to water, Pb²⁺ and Cl⁻ ions are produced following Ksp equilibrium:
PbCl₂(s) ⇄ Pb²⁺ + 2Cl⁻
Ksp = [Pb²⁺] [Cl⁻]²
If an excess of PbCl₂ was added, an amount of Pb²⁺ is produced (X) and twice Pb²⁺ is produced as Cl⁻ (2X):
Ksp = [X] [2X]²
Ksp = 4X³
As X is the amount of Pb²⁺ = 2.8x10⁻²M:
Ksp = 4(2.8x10⁻²)³
Ksp = 8.8x10⁻⁵Liquid methanol (CH3OH) reacts with oxygen gas to form carbon dioxide gas and water vapor. Express your answer as a chemical equation. Identify all of the phases in your answer.
Answer:
[tex]2CH_3OH_{(l)} + 3O_2_{(g)} --> 2CO_2_{(g)} + 4H_2O_{(g)}[/tex]
Explanation:
The reaction between methanol and oxygen can be expressed as an equation below:
[tex]CH_3OH + O_2 --> CO_2 + H_2O_[/tex]
However, the equation is not balanced as the number of the molecule of each atom on the right-hand side and the left-hand side is not the same. The balanced equation showing the phases of all the reactants and products is as below:
[tex]2CH_3OH_{(l)} + 3O_2_{(g)} --> 2CO_2_{(g)} + 4H_2O_{(g)}[/tex]
Two molecules of liquid methanol react with three molecules of oxygen gas to give 2 molecules of carbon dioxide gas and four molecules of water vapor.
What type of elements is on the right side of a Periodic Table?
What type is on the left?
Answer:
the right side of the periodic table are metals while the left side are non metals (with the exception of hydrogen)
he solubility of oxygen gas in water at 25 °C and 1.0 atm pressure of oxygen is 0.041 g/L. The solubility of oxygen in water at 2.5 atm and 25 °C is ________ g/L.
Answer:
0.1025 g/L
Explanation:
From the question above,
The solubility of oxygen gas in water at 25°c and 1.0 atm pressure is 0.041g/L
Henry's law states at a constant temperature the solubility of a gas is proportional to the pressure
Since the temperatures are both similar (25°c) then, the solubility of oxygen in water at 2.5 atm can be calculated as follows
= 0.041/1.0 × 2.5
= 0.041×2.5
= 0.1025 g/L
Hence the solubility of oxygen in water at 2.5 atm and 25°c is 0.1025 g/L
Calculate the pH and the pOH of an aqueous solution that is 0.020 M in HCl(aq) and 0.085 M in HBr(aq) at 25 °C.
Imagine that you're doing an experiment to determine how the running speed
of a hamster depends on the weight of the hamster. When plotting your data,
what variable should be on the y-axis?
A. Speed of hamster
B. Color of hamster
C. Weight of hamster
D. Type of hamster
What is the wavelength, in nanometers, of light with a frequency of 5.89 x 10¹⁴ s⁻¹?
Answer:
≅ 50, 909 nm
Explanation:
Wavelength, λ = [tex]\frac{speed}{freq}[/tex]
Given:
speed of light = [tex]3*10^{8} m/s[/tex]
f = 5.89 × [tex]10^{14}[/tex]
∴ λ = 3×[tex]10^{8}[/tex] / 5.89 × [tex]10^{14}[/tex]
= 0.0000509 m ≅ 50, 909 nm
Let me know if you need further assistance
calculate the potential of the electrochemical cell and determine if it is spontaneous as written at
Hello. This question is incomplete. The full question is:
Calculate the potential of the electrochemical cell and determine if it is spontaneous as written at 25 ∘C . Cu(s) || Cu2+(0.14 M) ‖‖ Fe2+(0.0040 M) || Fe(s) E∘Cu2+/Cu=0.339 VE∘Fe2+/Fe=−0.440 V Ecell= V Is the electrochemical cell spontaneous or not spontaneous as written at 25 ∘C ? not spontaneous spontaneous
Answer:
Ecell = -0.825v
Negative results indicate that the electrochemical cell is not spontaneous.
Explanation:
You will find the result by doing the following calculation:
Cu2 + = 0.14M
Fe2 + = 0.0040M
Eº Cu2 + / Cu = 0.339V
Eº Fe2 + / Fe = -0.440V
Electron change ............ n = 2
Cu // Cu2 + (0.14M) // Fe2 + (0.0040M) / Fe (s)
Cu + Fe2 + ----> Fe (s) + Cu2 + (aq)
You should now use the formula =
Eºcell = Eº anode - Eº cathode ------> Eº = Eº (Fe2 + / Fe) - Eº (Cu2 + / Cu)
Eº Cell = -0.440 - 0.339 = -0.779V
E cell = EºCell - (0.0591 / n) log (Cu2 + / Fe2 +)
E cell = -0.779 - (0.0591 / 2) log (0.14 / 0.0040)
Ecell = -0.825
What is science in 5 sentences
Answer:
Science is both boon and curse for living beings.
Science is the action to find out any fact regarding the natural world.
Science gives accurate facts, formulas, laws and theories.
Science has many major fields like chemistry, physics, biology etc.
Science is valued by society because the application of scientific knowledge helps to satisfy many basic human needs and improve living standards.
The estimated costs for remodelling the interior of an apartment are: three 1-gallon cans of paint at $13.69 each, two paint brushes at $9.53 each, and $135 for a helper. The total estimated cost with the appropriate significant figures is $
Answer:
$195
Explanation:
Step 1: Given data
Cost of a 1-gallon can of paint (cC): $13.69Number of 1-gallon cans of paint (nC): 3Cost of a paint brush (cB): $9.53Number of paint brushes (nB): 2Cost of a helper (cH): $135Number of helpers (nH): 1Step 2: Calculate the total estimated cost for remodelling the interior of an apartment
We will use the following expression.
C = cC × nC + cB × nB + cH × nH
C = $13.69 × 3 + $9.53 × 2 + $135 × 1
C = $195
Convert a speed of 259 cm/s to units of inches per minute. Also, show the unit analysis by dragging components into the unit‑factor slots.
Answer:
[tex]6118.11\frac{in}{min}[/tex]
Explanation:
Hello,
In this case, by knowing that 1 inch equals 2.54 cm and 60 seconds equals 1 min, the resulting value results:
[tex]=259\frac{cm}{s}*\frac{1in}{2.54cm}*\frac{60s}{1min}\\ \\=6118.11\frac{in}{min}[/tex]
Best regards.
How many significant figures are in the quantity 12.0 mL?
O A. 1
B. 2
C. 3
O D. 12
Answer:
C. 3
Explanation:
12.0 - 3 significant figures 1,2 and 0, because 0 is after decimal point.
identify balance chemical equation from the following
C+O2=CO2
H2+O2=H2O
2PbO+C=Pb+CO2
Fe2O3+2Al=Al2CO3+2Fe
Answer:
C+O2=CO2
Explanation:
no.of atoms on reactant side= no.of atoms on product side
MgSO4(aq) + 2NaOH(aq) Mg(OH)2(s) + Na2SO4(aq) i. Write the complete ionic equation from the balanced equation. (3 points) Please help!
Answer:
Mg²⁺(aq) + SO₄²⁻(aq) + 2Na⁺(aq) + 2OH⁻(aq) → Mg²⁺(aq) + 2OH⁻(s) + 2Na⁺(aq) + SO₄²⁻(aq)
Explanation:
The complete ionic equation is the chemical equation where the chemical species in the aqueous phase (aq) are written as ions.
In the reaction:
MgSO₄(aq) + 2NaOH(aq) → Mg(OH)₂(s) + Na₂SO₄(aq)
MgSO₄ dissociates in Mg²⁺ and SO₄²⁻, NaOH in Na⁺ and OH⁻, Mg(OH)₂ doesn't dissociate because is as solid and NaSO₄ dissociates in Na⁺ and SO₄²⁻ ions.
That means the complete ionic equation is:
Mg²⁺(aq) + SO₄²⁻(aq) + 2Na⁺(aq) + 2OH⁻(aq) → Mg²⁺(aq) + 2OH⁻(s) + 2Na⁺(aq) + SO₄²⁻(aq)
What volume of 1.25 M sodium hydroxide (NaOH) solution can be prepared using 60.0 g of sodium hydroxide? (The mass of one mole of NaOH is 40.0 g.)
0.667 L
0.833 L
1.20 L
1.88L
Answer:
The answer is
1.20 LExplanation:
Since the concentration , mass and molar mass of NaOH has been given we use the formula
[tex]C = \frac{m}{M \times v} [/tex]To find the volume
where
C is the concentration
m is the mass
M is the molar mass
v is the volume
Making volume the subject we have
[tex]v = \frac{m}{C \times M} [/tex]From the question
C = 1.25 M
m = 60 g
M = 40.0 g/mol
Substitute the values into the above formula and solve for the volume
We have
[tex]v = \frac{60}{1.25 \times 40} \\ v = \frac{60}{50} \\ v = \frac{6}{5} [/tex]We have the final answer as
Volume = 1.20 LHope this helps you
nder what reaction conditions does the electrophilic chlorination of aromatic compounds usually occur
Answer:
Cl2/FeCl3
Explanation:
The electrophilic chlorination of aromatic compounds proceeds in the presence of Cl2/FeCl3.
The function of the Lewis acid FeCl3 is to 'activate' the chlorine molecule towards electrophilic substitution. This occurs by the formation of a 'chlorine cation' which attacks the aromatic ring followed by deprotonation of the aromatic ring to retain the aromaticity of the compound.
The change that happen the piece of paper during the burning process?
Answer: Chemical
Explanation:
When paper is burned, it creates a chemical change.
Answer:
Explanation:
Hey, there!!
The answer is chemical change.
When the paper is burned it changes into an ash. Which is a chemical change. { as it can't be reversed }.
Hope it helps...