Answer:
[tex] \boxed{ \sf \: m = 1.866 \: grams}[/tex]
Explanation:
Given:
Change in temperature ∆T= -74.14°C
Heat(Energy) released Q= 578.7 joules
Specific heat capacity s = 4.184 J/(g·°C)
To find:
Mass of the sample (m)=?
Solution:
[tex] \sf s= \frac{Q}{m \cdot \Delta T} \\ \sf \: Substituting \: the \: given \: parameters \\ \sf 4.184 = \frac{578.7}{m \times ( - 74.14)} \\ \sf m = \frac{578.7}{4.184 \times ( - 74.14)} \\ \sf m = \frac{578.7}{310.20176} \\ { \sf m = 1.8655 \approx1.866 \: grams}[/tex]
Since, we need the answer in 4 significant figures,
[tex] \boxed{ \sf \: m = 1.866 \: grams}[/tex]
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Calculate the pH of the following aqueous solution:
0.35 M NaF (pKa for HF = 3.14)
I'm pretty sure I know how to calculate the pH by itself, but I am confused on how to get the equation. I'm not sure what HF has to do with this, other than it's an acid. I'm probably overthinking it because it's worded differently. Thanks in advance!
The pH of an aqueous solution that has a concentration of 0.35 M NaF and pKa for HF = 3.14 is 3.6.
How to calculate pH?The pH of a solution refers to the degree of acidity or alkalinity of the solution. It can be calculated using the Henderson-Hasselbalch Equation as follows:
pH = pka + log ([A-]/[HA])
Where;
A- = conjugate baseHA = weak acidpH = pKa + log([F-]/[HF])
pH = 3.14 + log(1/0.35)
pH = 3.14 + 0.4559 = 3.595
Therefore, the pH of an aqueous solution that has a concentration of 0.35 M NaF and pKa for HF = 3.14 is 3.6.
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Put the appropriate processes to their respective bins
Answer:
Remember
Endo = To EnterExo = To ExitThermic = HeatA sparkler burning is an exothermic reaction
Sparkler burning is an exothermic reaction and so the sign of the ΔH must be negative (–∆H) indicating that heat was released.
Ice melting is an endothermic reaction (+∆H) because the ice absorbs (heat) energy, which causes a change to occur.
Acetone evaporating from skin is an endothermic reaction (+∆H). Because, molecules that are evaporating are absorbing heat. So, evaporation is called endothermic.
Which statement is an opinion expressed in "Stick to Real Microscopes"?
A) Smartphone microscopes are not great scientific tools.
B) Many real microscopes cost between $150 and $300.
C) A fairly good real microscope can enlarge objects up to 2000 times their actual size.
D) It is quite inexpensive to turn a smartphone into a microscope.
Answer:it’s Smartphone microscopes are not great scientific tools.
Explanation:
The statement expressed in stick to real microscopes Smartphone microscopes are not great scientific tools.
What is scientific tools?Getting to use all the great tools is one of the best parts of constructing something. Power saws, drills, and electric sanders are tools that builders employ to transform basic materials into original designs.
Scientists employ tools to achieve their goals, just like builders do. Researchers can do experiments, make observations, and take precise measurements with the aid of scientific gear.
In this session, we'll talk about some basic scientific instruments that you could find in the science lab at your school, as well as some more sophisticated instruments that biologists use to study the world around us.
Therefore, The statement expressed in stick to real microscopes Smartphone microscopes are not great scientific tools.
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A glass tube contains mercury. What would be the height of the column of mercury which would create pressure equal to 1.00 atm
Since 1.00 atm is equal to 760 mmHg, the height of the column of mercury which would create pressure equal to 1.00 atm is 760 mm or 76 cm
What are the units of pressure?Pressure is defined as the force acting perpendicularly per unit area of a surface.
The units of pressure include;
millimetres of mercury, mmHgaatmospheres, atm,pascals, PaNewtons per square metre, N/m^21 atmosphere is equal to 760 mmHg.
Therefore, the height of the column of mercury which would create pressure equal to 1.00 atm is 760 mm or 76 cm
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What is the equilibrium constant K at 25°C for an electrochemical cell when E° = +0.0140 V and n = 2?(F = 96,500 J/(V･mol), R = 8.314 J/(mol･K))
The equilibrium constant of the electriochmeical cell as shown is 2.976.
What is the equilibrium constant?The equilibrium constant of a reaction shows the extent of the conversion of the reactants to products.
Now we know that;
ΔG = -nFE°cell
n = 2
F = 96,500 J/(V･mol)
E°cell = +0.0140 V
ΔG = -(2 * 96,500 * 0.0140)
ΔG = -2702 J
But;
ΔG = -RTlnK
lnK = -(ΔG/RT)
K = e^[-(ΔG/RT))
K = e^[-(( -2702)/8.314 * 298]
K = 2.976
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Consider the following reaction where Kc = 55.6 at 698 K.
H2(g) + I2(g) 2HI(g)
A reaction mixture was found to contain 2.29×10-2 moles of H2(g), 3.80×10-2 moles of I2(g) and 0.254 moles of HI(g), in a 1.00 liter container.
Is the reaction at equilibrium?
If not, what direction must it run in order to reach equilibrium?
The reaction quotient, Qc, equals
.
The reactionfill in the blank 2
A. must run in the forward direction to reach equilibrium.
B. must run in the reverse direction to reach equilibrium.
C. is at equilibrium.
Answer:
B
No the reaction is not at equilibrium
The reaction must run to the left (reactants) to reach equilibrium
Qc = 74.14
Explanation:
Qc = (0.254)^2 / ((2.29 x 10-2)(3.8 x 10-2))
Qc = 74.14
74.14 > 55.6
Qc > Kc
Why is it important for scientist to be objective when using the design process like the scientific method when doing there investigations?
Answer:
Scientists use the scientific method to make testable explanations and predictions about the world. A scientist asks a question and develops an experiment, or set of experiments, to answer that question. Engineers use the engineering design process to create solutions to problems.
plese help
Using the rules that you learned during the session, what is the answer to the following question?
55.78 * 23.7
Answers
A) 1,322
B) 1,320
explain:
Calculate AHræn for the following reaction
2 AX (g) + 7 BY (g) →4AY (g) + 6 BX (g)
Use the following AHformation values for AX, BY, AY and BX
AX: AHformation = -80 kJ/mol
BY: AH formation = 57 kJ/mol
AY: AHformation = -379 kJ/mol
BX: AHformation = -251 kJ/mol
Answer:
60ax 70by 67ay ah251
Explanation:
What is the molarity of a solution where 2.2 mol of KCl is dissolved to make 5.7 L of solution?
What is ∆G° for a redox reaction where 6 moles of electrons are transferred and E° =-2.25 V? (F = 96,500 J/(V･mol))
A redox reaction with E° = -2.25 V involving the transference of 6 moles of electrons has a ΔG° of 9.38 × 10⁵ J.
What is the standard Gibbs free energy?The standard Gibbs free energy (ΔG°) is a thermodynamical function that indicates the spontaneity of a reaction.
A redox reaction, in which 6 moles of electrons are transferred (n = 6 mol), has a standard cell potential (E°) of -2.25 V.
Knowing that the Faraday's constant is F = 96,500 J/V.mol, we can calculate the standard Gibbs free energy using the following expression.
ΔG° = - n × F × E°
ΔG° = - 6 mol × (96,500 J/V.mol) × (-2.25 V) = 9.38 × 10⁵ J
A redox reaction with E° = -2.25 V involving the transference of 6 moles of electrons has a ΔG° of 9.38 × 10⁵ J.
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How many Si atoms are there in 1.00 g of silicon
A solution is made by adding 15 g of sodium chloride into 150 g of water. What is the mass percentage of this sodium chloride in this solution?
Answer:
[tex]\sf \fbox {mass \:percentage \: = 9.09 \%}[/tex]
Explanation:
Given:
Mass of solute = 15g
Mass of solvent (Water)= 150g
To find:
Mass percentage of sodium chloride=?
Solution:
Let's find out the mass of overall solution first,
Mass of solution= Mass of solute+ mass of solvent
Mass of solution = 15+150= 165 gram
Now we know that,
[tex] \sf \: mass \:percentage \: = \frac{Mass \: of \: solute}{Mass of solution} \times 100 \\ \sf \: mass \:percentage \: = \frac{15}{165} \times 100 \\ \sf \: mass \:percentage \: = \frac{1500}{165} \\ \sf \fbox {mass \:percentage \: = 9.09 \%}[/tex]
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Which technique can be used to remove air bubbles from a syringe? a) Hold the syringe downward, shake vigorously for 10 seconds, and expel the bubbles through the needle using the syringe plunger. Hold the syringe upright, provide a firm tap or flick to the b) barrel, and expel the bubbles through the needle using the syringe plunger. Hold the syringe upright, shake vigorously for 10 seconds, c) and expel the bubbles through the needle using the syringe plunger. Hold the syringe downward, provide a firm tap or flick to the d) barrel, and expel the bubbles through the needle using the syringe plunger.
Answer:
Point the syringe upright and tap firmly to move the bubbles to the top and expel by pushing the plunger
Explanation:
If you hold the syringe upside down the bubbles will end up at the bottom of the syringe by the plunger since they float up when tapped
Which type of covalent bond is the least stable?
A.Covalent bonds
B.Double bonds
C.Single bonds
D.Triple Bonds
Answer:
D because: A Triple bond is when three pairs of electrons are shared between two atoms in a molecule. It is the least stable out of the three general types of covalent bonds.
Hey guys i needed some help on this
Based on the bond energies given, the standard enthalpy of the reaction, ΔH°(rxn) is -296 kJ.
What is standard enthalpy change of a reaction?The standard enthalpy change of a reaction is the energy changes involved when substances react under standard conditions to form products.
ΔH°(rxn) = sum of the bond energies of bonds being broken - sum of the bond energies of the bonds being formed.The standard enthalpy of the reaction, ΔH°(rxn) is calculated as follows:
Sum of energy of bonds broken = 839 + (2 × 413) + (432 × 2) = 2529 kJ
Sum of energy of bonds formed = 347 + (6 × 413) = 2825 kJ
ΔH°(rxn) = (2529 - 2825) kJ
ΔH°(rxn) = -296 kJ
Therefore, the standard enthalpy of the reaction, ΔH°(rxn) is -296 kJ.
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For the reaction H2O) =H% + OH", if x moles of H and y moles of OH are formed K. is y A. *?/(1 – x) C. 1/xy D. xy
Answer: Correct option is B)
The standard enthalpy change of formation of a compound is the enthalpy change which occurs when one mole of the compound is formed from its elements under standard conditions. The equation showing the standard enthalpy change of formation of water is
H
2
(g)+
2
1
O
2
(g)⟶H
2 ↑
O(l) 1 mole of water formed.
∴ Enthalpy of formation is −X2kJ/mol.
________________________________________________________
Explanation:I hope this helped
An electron in the n=7 level of the hydrogen atom relaxes to a lower energy level, emitting light of 93.1 nm.
What is the value of n for the level to which the electron relaxed?
answer:
nf=2
Explanation:
It is given that,
Initially, the electron is in n = 7 energy level. When it relaxes to a lower energy level, emitting light of 397 nm. We need to find the value of n for the level to which the electron relaxed. It can be calculate using the formula as :
Which unit is used to measure the distance between galaxies? Question 3 options: kilometers decades years light years
Answer:
light years
Explanation:
light year is the DISTANCE light travels in one year ...a very large distance
Answer:
light years
Explanation:
since distance between galaxy space ,objects .
Which of the following are true about photosynthesis and cellular respiration. (Select all that apply.)
The products of one process are the reactants of the other.
The relationship between them enables life to survive as we know it.
They both happen only in plants.
They both take place in human cells.
Answer:
2 and 4 are the best answers
Explanation:
Answer:
A and B
Explanation:
Took the k12 test.
Kelly's spring scale indicates that it takes 4.9 newtons of force to lift the mass directly.
With the lever, she plans to add masses to the right side until it is able to lift the 500-gram mass 10 cm.
Consider the location of the lever's fulcrum. When Kelly has added enough mass to the right side, she should expect the downward force exerted on the right side of the lever to be
A.
equal to 500 grams.
B.
less than 4.9 newtons.
C.
equal to 4.9 newtons.
D.
greater than 4.9 newtons.
Answer:
less than 4.9 newtons Explanation:
10. Boron has two naturally occurring isotopes, 10B with an atomic mass of 10.0129370amu and 11Bwith an atomic mass of 11.0093054amu. The atomic mass of boron is 10.81 (from the periodic table). The percent abundances of the boron isotopes are __________% 10Band __________% 11B.
Explanation:
allowing 20% discount on the market price of a watch the value of the watch will be rs 2376 when a VAT of 10% is added ,find it's market price
a 21.0 kg rock rests on the edge of a cliff 32.0 m high. how much gravitational potential energy does the rock have
Explanation:
Formula for Potential energy=mgh mass* gravity*height
21kg × 10 ×32=6720joules
If a 21.0 kg rock rests on the edge of a cliff 32.0 m high, the gravitational potential energy gained by the rock would be 6585.6 Joules.
What is mechanical energy?Mechanical energy is the combination of all the energy in motion represented by total kinetic energy and the total stored energy in the system which is represented by total potential energy.
As given in the problem a 21.0 kg rock rests on the edge of a cliff 32.0 m high, then we have to calculate the potential energy gained by the rock,
The potential energy of the rock = 21 × 9.8 × 32
= 6585.6 Joules.
Thus ,If a 21.0 kg rock rests on the edge of a cliff 32.0 m high, the gravitational potential energy gained by the rock would be 6585.6 Joules.
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8. Thermal Energy is?
A. Kinetic
B. Potential
c. Potential and Kinetic
D. Neither Potential and Kinetic
Thermal energy is the sum of the kinetic and potential energy of all the particles in an object. The figure shows that if either potential or kinetic energy increases, thermal energy increases.
hope it really helps...!!!
The rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by_______
growing slowly over time, on their surface.
PLSSS HELPP ASAPP
Answer:
The rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by Metamorphic Rock growing slowly over time, on their surface.
The rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by Metamorphic rocks
growing slowly over time, on their surface.
Consider the following generic chemical equation.
A+3B→C
What is the limiting reactant when each of the following amounts of A and B are allowed to react?
A. 1 mol A; 4 mol B
B. 2 mol A; 3 mol B
C. 0.5 mol A; 1.6 mol B
D. 24 mol A; 75 mol B
Answer:
[tex]\fbox{ A) A \: is \: limiting \: reactant }[/tex]
[tex]\fbox{ B) B \: is \: limiting \: reactant }[/tex]
[tex]\fbox{ C) A \: is \: limiting \: reactant }[/tex]
[tex]\fbox{ D) A \: is \: limiting \: reactant }[/tex]
Explanation:
Given equation:
[tex]A+3B \rightarrow \: C [/tex]
To find:
Limiting reactant for corresponding number of moles=?
Solution:
We know that the liming reactant is any atom, ion or molecule which is completely consumed during a reaction and other reactant is still left in reactant vessel.
For the given reaction A+3B→C
for every one mole of A three moles of B are required.
﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌
in A) there is one mole of A and 4 mole of B,
if 1 mole of A will react with 3 moles of B, 1 mole of B will be still there in reaction, the reactant was completely consumed is A which is limiting reactant.
﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌
in B) there is 2 mole of A and 3 mole of B,
if 1 mole of A will react with 3 moles of B, 1 mole of A will be still there in reaction, the reactant was completely consumed is B which is limiting reactant.
﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌
in C) there is 0.5 mole of A and 1.6 mole of B
if one mole of A requires three moles of B to complete the reaction then,
0.5 moles of A will require 1.5 moles of B
if 0.5 mole of A will react with 1.6 moles of B, 0.1 mole of B will be still there in reaction, the reactant was completely consumed is A which is limiting reactant.
﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌
in D) there is 24 mole of A and 72 mole of B
if one mole of A requires three moles of B to complete the reaction then,
24 moles of A will require 72 moles of B.
if 24 mole of A will react with 75 moles of B, 3 mole of B will be left over in reaction, the reactant was completely consumed is A which is limiting reactant.
﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌﹌
[tex]\fbox{ A) A \: is \: limiting \: reactant }[/tex]
[tex]\fbox{ B) B \: is \: limiting \: reactant }[/tex]
[tex]\fbox{ C) A \: is \: limiting \: reactant }[/tex]
[tex]\fbox{ D) A \: is \: limiting \: reactant }[/tex]
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Could someone please tell me the name of this branched alkane?
Answer:
2-Methylhexane
Explanation:
A 0.15 M NaOH solution has a volume of 0.125 L but is then diluted to 0.15 L. What is the concentration of the new solution
Answer:
.125 M
Explanation:
.15 M/L * .125 L = .01875 moles
now dilute to 150 cc (by adding 25 cc)
.01875M / (150/1000) = .125M
The cylinder of a car's engine has a volume of 0.6250 L when the piston is at the bottom of the cylinder. When the piston is at the top of the cylinder the volume is 0.0600 L. If the cylinder is filled with air at an atmospheric pressure of 765.1 mm Hg the piston is at the bottom, what is the pressure in units of kPa when the piston is at the top of the cylinder?
The new pressure in the cylinder of the car engine as the piston is moved to the top is 1062.55kPa
Boyle's lawBoyle's law states that "volume of a given quantity of gas is inversely proportional to its pressure as long as temperature remains constant.
It is expressed as;
P₁V₁ = P₂V₂
Given the data in the question;
Initial volume V₁ = 0.6250LNew volume V₂ = 0.0600LInitial pressure P₁ = 765.1mmHg = 1.0067107atmNew pressure P₂ = ?To determine the new pressure as the piston is at the top of the cylinder, we substitute our given values into the expression above.
P₁V₁ = P₂V₂
P₂ = P₁V₁ / V₂
P₂ = ( 1.0067107atm × 0.6250L ) / 0.0600L
P₂ = 0.629194188Latm / 0.0600L
P₂ = 10.4865698atm
P₂ = 1062.55kPa
Therefore, the new pressure in the cylinder of the car engine as the piston is moved to the top is 1062.55kPa
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Identify the type of energy conversion represented by each picture.
solar energy to light energy
electric energy to light energy
electric energy to heat energy
wind energy to electric energy
[tex]\qquad\qquad\huge\underline{{\sf Answer}}[/tex]
The given pictures show conversion of energy from one form to another.
#Picture 1Electric energy to Heat energy
#Picture 2Wind energy to electric energy
#Picture 3Solar energy to light energy
#Picture 4Electric energy to light energy