Answer:
KOH molar mass = 39 + 16 + 1 = 56g
To make 1 L of 1M soln needs 56g KOH
To make 500mL 1M needs 56/2 = 28g
To make 500mL 0.2M needs 28 x 0.2gn:
Explanation:
The weight of KOH are required to prepare 500. mL of 0.450 KOH solution is 12.6 gm
What is Molarity ?Molar concentration is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution.
In chemistry, the most commonly used unit for molarity is the number of moles per liter, having the unit symbol mol/L or mol/dm³ in SI unit.
Molar mass of KOH = 39 + 16 + 1 = 56g
To make 1 L of 1M soln needs = 56g KOH
To make 500mL 1M needs 56/2 = 28g
To make 500mL 0.450 M needs = 28 x 0.450
= 12.6 gm
Therefore, The weight of KOH are required to prepare 500. mL of 0.450 KOH solution is 12.6 gm.
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a lizard drinks water that contains H-2. The H-2 decays and approximately 6.25% remain after 30 seconds. What is the 1/2 life for H-2?
Answer:
7.5 sec.
Explanation:
A = A₀e⁻^kt => k = ln(A/A₀)/-t => ln(6.25/100)/-30s = 0.0924 s⁻¹
k·t₀.₅=0.693 => t₀.₅=0.693/k = (0.693/0.0924)s = 7.5 s
The half life of an isotope can be calculated from the decay constant of . The half life of H-2 if only 6.25 % remains after 30 seconds is 17.25 seconds.
What is half life?Unstable radioactive isotopes undergo nuclear decay by emitting charged particles such as alpha particles or beta particles. The nuclear decay process results in a stable isotope or new atom.
It is given that the final amount of the isotope is 6.25% and and the time taken for the decay is 30 seconds. Let the initial amount be 100%.
The decay constant k can be calculated as follows:
k = 1/t log (100/6.25)
= 1/30 s log 16
= 0.0401 s⁻¹
Now, the half life time can be determined as below:
half life t1/2 = 0.693 /k
= 0.693 /0.0401 s⁻¹
= 17.25 seconds.
Hence, the half life time of the given H-2 isotope is 17.25 seconds.
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A sample of 0.300 moles of nitrogen occupies 0.600 L. Under the same conditions, what number of moles occupies 1.200L
Answer:
0.600 moles has volume 1.200L
Explanation:
The volume is numerically double the moles
0.600 mol occupies 1.200L
Mathematically:
V1/moles1 = V2/moles2
1.200L / moles1 = 0.600L/ 0.300mol
Moles 0.600L = 1.200L * 0.300mol
Moles = 1.2000L *0.300 mol / 0.600L
moles = 0.600 moles.
A rectangular solid has the following measurements 6 cm, 10 cm, and 5 cm. what is the volume of the solid?
Consider separate solutions of NaOH and KClmade by dissolving 100.0 g of each solute in 250.0 mL of solution. Calculate the concentration of each solution in units of molarity.
Answer:
Explanation:
MW of NaOH = 40 g/mol
MW of KCl = 74.55 g/mp;
250 mL = .25 L
100g NaOH / 40 g = 25 mol
100g KCl/ 74.55g = 1.34 mol
Molarity of NaOH: 25/.25 = 100M
Molarity of KCl: 1.34/.25 = 5.36 M
100M is the concentration of NaOH.
5.36 M is the concentration of KCl.
Define the molarity of a solution.Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per litres of a solution.
The scientific noun molarity describes the concentration of a substance as measured by the number of moles divided by the volume of the solution in litres.
[tex]Molality = \frac{Moles \;solute}{Volume\; of \;the \;solution \;in \;litres}[/tex]
Molecular weight of NaOH = 40 g/mol
Molecular weight of KCl = 74.55 g/mp;
250 mL = .25 L
100g NaOH ÷ 40 g = 25 mol
100g KCl ÷ 74.55g = 1.34 mol
Molarity of NaOH: 25 ÷ .25 = 100M
Molarity of KCl: 1.34 ÷ .25 = 5.36 M
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Which are functions of the stomata in the leaves of seed plants? Check all that apply.
-reduce water loss
-make glucose
-absorb sunlight
-take in carbon dioxide
-produce oxygen
NEED CORRECT ANSWER ASAP BEING TIMED
Answer:
Take in carbon dioxide, reduces water loss, and produce oxygen.
Explanation: Hi! I've learned about these things in the past, really tough stuff! Hopefully this helps, I believe the three options above are correct, only one I'm possibly questioning is producing oxygen. Good luck!
Answer:
Take in carbon dioxide, reduces water loss
Explanation:
The 38 elements in groups 3 through 12 of the periodic table are called "Alkaline Earth Metals" O True O False
Answer:
FALSE
they're called transition metals
Answer:
false
Explanation:
The 38 elements in groups 3 through 12 of the periodic table are called "transition metals." As with all metals, the transition elements are both ductile and malleable, and conduct electricity and heat.
In the reaction 2 Na(s) + F2(g) --> 2NaF (s), Given 12.5 g of fluorine with enough sodium, what mass of sodium fluoride forms?
Answer:
the mass of sodium fluoride is 15
Explanation:
One mole of F₂ or 38 g produces two moles or 84 g of NaF. Hence, 12.5 g of F₂ will produce 27.6 g of NaF.
What is sodium fluoride?Sodium fluoride is an ionic compound formed by the reaction of sodium metal and fluorine atom . Sodium metal loses one electron to fluorine and thus two moles of sodium and fluorine molecule produces 2 moles of NaF.
The molar mass of F₂ is 38 g. The molar mass of NaF is 42 g/mol. Thus mass of two moles of NaF is 84 grams. As per the balanced reaction, one mole or 38 g of F₂ produces two moles or 84 g of NaF. Thus mass of NaF is calculated as follows:
Mass of NaF = (12.5 g × 84 g) /38 g.
= 27.6 g.
Therefore, the mass of NaF produced by 12.5 g of F₂ in this reaction is 27.6 grams.
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How many grams of NO2 are needed to form 88.0 g of HNO3?
Answer:
64.4g
Explanation:
The chemical reaction that will produce HNO₃ from NO₂ is given below:
3NO₂ + H₂O → 2HNO₃ + NO
Given;
Mass of HNO₃ = 88g
Now;
To solve this problem, find the number of moles of HNO₃;
Number of moles = [tex]\frac{mass}{molar mass}[/tex]
Molar mass of HNO₃ = 1 + 14 + 3(16) = 63g/mol
Number of moles = [tex]\frac{88}{63}[/tex] = 1.40mol
From the balanced reaction;
2 mole of HNO₃ is produced from 3 mole of NO₂
1.4 mole of HNO₃ will be produced from [tex]\frac{1.4 x 3} {2}[/tex] = 2.1mole of NO₂
Mass of NO₂ = number of moles x molar mass
Molar mass of NO₂ = 14 + 2(16) = 46g/mol
Mass of NO₂ = 1.4 x 46 = 64.4g
Using the model of the Periodic Table, which two elements pictured have similar chemical properties?
Answer:
C) 1 and 3
Explanation:
A period in the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. ... Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law.
During the process of diluting a solution, ________.
a. water is removed from the concentrated solution
b. the amount of solvent does not change
c. the amount of solute does not change
d. the volume of the solution does not change
e. there is more solute in the concentrated solution
What is the oxidation number of vanadium in V₂O₅?
Answer:
+4
Explanation:
Treatment of the ammonium metavanadate with hot hydrochloric acid partly reduces the vanadium to the +4 oxidation state in the form of the VO2+ ion.
In vanadium oxide we increase both sides by 4. And we discover that x is equal to five. The vanadium's oxidation number is + 5.
What is oxidation ?
Loss of electron is called as oxidation. and addition of oxygen molecule is also the oxidation.
When an object comes into touch with oxygen or another oxidizer, a chemical reaction occurs. Rust and the brown color of a sliced apple are both examples of oxidation.
Antoine Lavoisier used the term "oxidation" to describe the reaction of a material with oxygen. The meaning was later expanded to cover additional reactions in which electrons are lost, regardless of whether oxygen was present, after it was realized that the substance loses electrons when it is oxidized.
Thus, the oxidation number of vanadium in V₂O₅ is + 5.
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PLEASE HELPPPP! HOW DO I DO THIS???
1. Calculate the amount of heat released when a 225 g sample of gold cools from 86.0oC to 32.5oC. The specific heat of gold is 0.129 J/goC
2. A 19.6 g sample of a metal was heated to 61.67oC. When it was placed into 26.7 g of water in a constant pressure calorimeter, the temperature of the water rose from 25.00oC to 30.00oC. Determine the specific heat of the metal if the specific heat of H2O(liq) is 4.18 J/goC. Ignore any contribution from the container.
Answer:
1552.83J Released
Explanation:
1. mass/m=225
Initial temp:86C, final:32.5C
Changed Temp: 32.5-86= -53.5C
s=0.129 J/gC
Formula: q= m times s times changed Temp.
q=(225)(0.129)(-53.5)
q= -1552.83 J
q=1552.83 J Released
If you add 90 mL of 0.15M stock solution, to 10 mL of water, what is the new concentration?
0,15 moles of NaOH-------in------------1000ml
x moles of NaOH------------in--------100ml
x = 0,015 moles of NaOH
final volume = 150ml
0,015 moles of NaOH---in-------150ml
x moles of NaOH--------------in-----1000ml
x = 0,1 moles of NaOH
answer: 0,1mol/dm³ (molarity)
Which term refers to the loss of fertile soil from drying out?
erosion
desertification
depletion
overuse
Answer:
Desertification
Explanation:
I took the test
Desertification is the loss of fertile soil from drying out.
What is desertification?Desertification is the process where by the fertile soil is washed away and dry out because of overexposure and absence of trees to hold the soul together and drought.
Therefore, Desertification is the loss of fertile soil from drying out.
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The picture below shows a specific nuclear reaction occurring. What best describes the unlabeled particle shown at the bottom of the picture that is released during this reaction? *
Calculate the volume in liters of 0.558 M KOH necessary to titrate 0.016 moles of hydrochloric acid, HCl, to a phenolphthalein end-point.
Answer:
Explanation:
Let the volume required be v litre .
moles of KOH in v litre of .558 M of KOH = v x .558 moles
1 mole of KOH reacts with 1 mole of HCl
v x .558 moles of KOH reacts with v x .558 mole of HCl
v x .558 = .016
v = .016 / .558
= .02867 litre
= 28.67 mL .
An element has a half-life of 5.0 days. How many days would
pass before only 1/8th of the original amount of a sample of this
element remained?
Answer:
15 days
Explanation:
Given half-life = 5 days => k = 0.693/half-life = 0.693/5 days⁻¹
A = A₀e^-k·t => t = ln(A/A₀) / -k = ln(1/8) / -0.1386 days⁻¹ = 15 days
The element with half life of 5 days have the decay constant of 0.1386 dy⁻¹ will take 15 days to decay to its 1/8th part of initial amount.
What is half life ?Heavy unstable radioactive isotopes undergo nuclear decay by the emission of charged particles. Nuclear decay is a first order reaction.
Thus, the decay constant k = 1/t ln W0/Wt
where t is the time of decay, W0 be the initial amount and Wt be the amount after time t.
The half life of the element = 5 days.
decay constant = 0.693/t1/2
k = 0.693/5 days = 0.1386 days⁻¹.
The time taken to decay to 1/8th of its original amount is calculated as follows:
t = 1/k ln Wo/(Wo/8 )
= ln 8/0.1386 days⁻¹
= 15 days.
Therefore, the days before the element decay to its 1/8th of original amount is 15 days.
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Rank the following salts in order of increasing lattice energy: lithium chloride, calcium oxide, aluminum oxide, sodium chloride, barium oxide.
Please explain! Thank you.
Answer:
barium oxide < calcium oxide< sodium chloride < lithium chloride < aluminum oxide
Explanation:
The lattice energy can be defined as the change in internal energy accompanying the formation of a single mole of an ionic solid from its gaseous constituents at 0 K.
The lattice energy depends on the relative sizes of cations and anions in the compound. The smaller the cations and anions, the greater the lattice energy.
If we look as the proposed order of increasing lattice energy of the compounds; barium oxide < calcium oxide< sodium chloride < lithium chloride < aluminum oxide, we will notice that it follows the order of decrease in the sizes of both the ions, Ba^2+ > Ca^2+ > Na+ >Li+ > Al^3+.
The smaller the ions involved, the greater the lattice energy as one can see from the order listed above.
Barium oxide < calcium oxide< sodium chloride < lithium chloride < aluminum oxide is the rank of salts in the increasing order of their lattice energy.
What is lattice energy?Lattice energy is define as the amount of internal energy required for the formation of one mole of ionic compound by its constitute ions.
Lattice energy is inversely proportional to the size of ions present in the ionic compound. In the given question order of size of ions are:
Ba²⁺ > Ca²⁺ > Na⁺ > Li⁺ > Al³⁺
From the above order it is clear that size of aluminum ion is smallest, so lattice energy for this ionic compound is more and sequence of salts in the increasing order of lattice energy is as follow:
barium oxide < calcium oxide< sodium chloride < lithium chloride < aluminum oxide
Hence, Aluminum oxide has highest lattice energy and barium oxide has minimum.
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a gas container with a volume of 271 mL contains 0.26 moles of gas. Gas is added to the container so that it now contains 0.80 mole of gas. what is the new volume in milliliters
Answer:
V₂ = 833.85 mL
Explanation:
Given data:
Initial volume V₁= 271 mL
Initial number of moles n₁= 0.26 mol
Final number of moles n₂= 0.80 mol
Final/new volume V₂ = ?
Solution:
V₁/n₁ = V₂/n₂
Now we will put the values in formula.
271 mL / 0.26 mol = V₂ / 0.80 mol
V₂ = 271 mL × 0.80 mol / 0.26 mol
V₂ = 216.8 mL.mol / 0.26 mol
V₂ = 833.85 mL
The survival of aquatic organisms depends on the small amount of O2 that dissolves in H2O . The diagrams above represent possible models to explain this phenomenon. Which diagram provides the better particle representation for the solubility of O2 in H2O , and why?
Answer:
Diagram 1
Explanation:
The solubility of the oxygen gas in water has to do with the interaction of the oxygen with the dipoles in water.
Water is a polar molecule having oxygen as the negative dipole and hydrogen as the positive dipole.
Water can interact with the oxygen atoms in the molecule via intermolecular hydrogen bonds with molecular oxygen as shown in diagram 1.
Object A has a molar heat of 31.2 J/mole∙°C and object B molar heat is 11.2 J/mole∙°C. Which object will heat up faster if they have the same mass and equal amount of heat is applied? Explain why.
Answer:
Substance B
Explanation:
Molar heat of A = 31.2J/mole.°C
Molar heat of B = 11.2 J/mole∙°C.
The molar heat of a substance is the amount of heat that must be added to a mole of a substance to raise the temperature by 1°C.
Substance B will heat up faster compared to A. It has a smaller molar heat compared to A. This suggests that it will require lesser heat to raise its temperature by 1°C.
You added 20 g of NaCl to 100g of water. What is the percent by mass of the solute? (Hint: You have not been given the total mass of the solution. This must be calculated
We are given:
Mass of solvent (water) = 100 grams
Mass of solute (NaCl) = 20 grams
Mass of the Solution:
Mass of Solution = Mass of Solute + mass of Solvent
100 + 20 = 120 grams
Mass Percent of NaCl:
We know that
mass percent of NaCl = (Mass of NaCl / Mass of Solution) * 100
replacing the variables
Mass% of NaCl = (20 / 120)*100
Mass% of NaCl = 100 / 6
Mass% of NaCl = 16.67%
Which one is being shown in this picture?
Answer:
B. REFRACTION.
Is shown in fig.
15. Which chemical equation below is not balanced?
O 3 MgSO4 + 2 Na3PO4 + Mg:(PO4), + 3 Na2SO4
O C6H12O6 + 6 0, → 6 C0, + 6 H2O
HBr + AgNO3 → HNO3 + AgBr
2 NaOH + HNO. → NaNO: + 2 H20
Explanation:
yea that doesn't look right you should maybe organize that all a lot more
A tea kettle on a hot burner. Point A is steam coming from the spout. Point B is the heat source. Use the drop-down menu to choose the type of thermal energy transfer shown at each point in the image. A: B:
Answer:
A : convection
B : conduction
Explanation:
Answer:
A. Convection
B. Conduction
Explanation:
QUESTION 5
What is a mixture?
O Contains one kind of particle and they DO NOT keep thier own identity and properties.
O Contains one kind of particle.
O Contains MORE than one kind of particle and they keep their own identity and properties.
O Contains MORE than one kind of particle and they DO NOT keep their own identity and properties.
Answer:
C
Explanation:
Cccccccccccccccccccc
Answer:
The third option.O contains more than one kind of particles anddd they keep their own identify and properties because the definition of mixture is a material made up of 2 or more different substances which are physically combined and identities are retained
can you help me please
Answer:
N- 7 protons, 14 mass number
Ca- 20 protons, 20 neutrons, 20 electrons
I- 53 protons, 127 mass number
Cr- Cr, 12 neutrons
Br- 34 protons, 35 electrons, 79 atomic mass
C + ZnO ➡️ Zn + CO2
How many moles of zinc will be produced when 0.13 moles ZnO react?
Answer:
0.12 moles of Zn will produced
Explanation:
Given data:
Number of moles of zinc produced = ?
Number of moles of ZnO react = 0.12 mol
Solution:
Chemical equation:
C + 2ZnO → 2Zn + CO₂
Now we will compare the moles of Zn with zinc oxide.
ZnO : Zn
1 : 2
0.12 : 0.12
0.12 moles of Zn will produced.
1. What type of battery was made by alternating layers of silver, zinc and blotting paper soaked in salt?
O voltaic piles
O lead acid batteries
O wet cell batteries
O dry cell batteries
Right answer gets a Brainly!
Answer:
voltaic piles
Explanation:
:3
Answer:
Ik someone already answered it correctly, but it is voltaic piles.
Explanation:
Write the balanced equation for the reaction that occurs when aluminum bromide is mixed with potassium sulfate forming potassium bromide and aluminum sulfate
Answer:
2AlBr₃ + 3K₂SO₄ → 6KBr + Al₂(SO₄)₃
Explanation:
Given species;
Reactants
Aluminum bromide = AlBr₃
Potassium sulfate = K₂SO₄
Products
Potassium bromide = KBr
Aluminum sulfate = Al₂(SO₄)₃
So, the reaction equation is given as:
AlBr₃ + K₂SO₄ → KBr + Al₂(SO₄)₃
To balance this chemical equation, let us an algebraic approach;
aAlBr₃ + bK₂SO₄ → cKBr + dAl₂(SO₄)₃
Conserving Al;
a = 2d
Conserving Br;
3a = c
Conserving K;
2b = c
Conserving S;
b = 3d
Conserving O;
4b = 12d
if a = 1;
c = 3
b = [tex]\frac{3}{2}[/tex]
d = [tex]\frac{1}{2}[/tex]
Now, multiply through by 2;
a = 2, b = 3, c = 6 and d = 1
2AlBr₃ + 3K₂SO₄ → 6KBr + Al₂(SO₄)₃