Answer:
about 5 hours
Explanation:
When doing this problem you mmust mulitiply 4 x 74 and divide the answer by 60 because 60=1 hour.
For each of the environments below: (1) identify your system and surroundings and (2) predict whether it would be endothermic or exothermic.a.Wood burningSystem:Surroundings:Enthalpy Change:b.Water freezingSystem:Surroundings:Enthalpy Change:c.Sweat evaporatingSystem:Surroundings:Enthalpy Change:d.Chemical hand-warmerSystem:Surroundings:Enthalpy Change:
Answer:
A) Wood burning
system : Wood.
surroundings : atmosphere
Enthalpy : Exothermic
B) Water Freezing system
System : Refrigerator
surroundings : water in the refrigerator
enthalpy change : Endothermic
C) Sweat evaporating
System : Human being
surroundings : Air nearby
Enthalpy change : exothermic
D) Chemical Hand-warmer
system : Hand warmer pack
Surroundings : human palms
Enthalpy Change : Exothermic
Explanation:
A) Wood burning
system : Wood
surroundings : atmosphere
Enthalpy : Exothermic
This system give away energy to its surroundings hence its enthalpy change is exothermic
B) Water Freezing system
System : Refrigerator
surroundings : water in the refrigerator
enthalpy change : Endothermic
The system absorbs heat from what is put inside(surroundings ) of it hence this is na endothermic system
C) Sweat evaporating
System : Human being
surroundings : Air nearby
Enthalpy change : exothermic
This is an exothermic reaction ( enthalpy change ) because the system gives out heat to the surrounding
D) Chemical Hand-warmer
system : Hand warmer pack
Surroundings : human palms
Enthalpy Change : Exothermic
There is movement of heat from the system to the surrounding hence it is an exothermic reaction
Which substance is soluble in water?
A reaction has a theoretical yield of 27.6 g. When the reaction is carried out, 13.4 g of the product is obtained. What is the percent yield?
A) 48.6 %
B) 206 %
C) 370 %
D) 64.7 %
Answer:
yee I'm excellent in maths and science
2. A chemical's flash point is the
- Rachel performed an investigation to study the thermal conductivity of four different materials. She started with four identically shaped rods—each made of a different material. Then, she placed one end of each rod into a pot of boiling water, which was at 100°C.
- After five minutes, Rachel measured the temperatures of the ends of the rods that were sticking up out of the pot to see whether they got hot. Her results are shown below.
Thermal Conductivity Investigation
Material Temperature of End of Rod After 5 Minutes
Material 1 41°C
Material 2 53°C
Material 3 98°C
Material 4 59°C
- Rachel knows that one of the materials is copper and that copper conducts thermal energy very well. Which of the materials is most likely copper?
A.
material 1
B.
material 3
C.
material 4
D.
material 2
Answer:
I will have the maths book
Answer:98
Explanation:
Reactants for a certain reaction are combined in a solution. Which solution
would have the most successful collisions and so enable the reaction to
proceed quickly?
A. A solution at low concentration and low temperature
B. A solution at high concentration and low temperature
O C. A solution at high concentration and high temperature
D. A solution at low concentration and high temperature
The correct answer is solution B!
2Na(s) + Cl2(g) - 2NaCl(s) + 822 kj
Answer:
Is there any other part to this question? If not I'm pretty sure the answer is 205.5 kJ
Explanation:
Answer:
822 kJ; 411 kJ/mol.
Explanation:
A chemist measures the enthalpy change during the following reaction: ()()()Use this information to complete the table below. Round each of your answers to the nearest kJ/mol. 1. ()()()Solution: given reaction is 2Na + Cl2 --> 2NaCl delta H = -822 KJ 1) 1/2Na + 1/4Cl2 --> 1/2NaCl divide the coficiant of given.
6. Menthol is a member of the terpene family of natural products. It exists in a (1R, 2S, 5R) form and a (IS, 2R, 5S) form. Are these two compounds enantiomers or diastereomers?
how many grams of silver chloride are produced from 15.0 g of silver nitrate
Answer:
4.2 g
Explanation:
What would happen to the position of the equilibrium when the following changes are made to the reaction below?
2HgO(s) ↔ Hg(l) + O2(g)
1.) The pressure on the system decreases.
Chlorofluorocarbons may be harming the ozone layer by ____.
a.
adding more ozone molecules
c.
destroying ozone molecules
b.
blocking ultraviolet radiation
d.
adding carbon dioxide molecules
Please select the best answer from the choices provided
Answer:
The awnser is C. Hope that helps!!!
A 250mL beaker is submerged in a large container of Liquid A and turned upside down, and another 250mL beaker is submerged and turned upside down in a large container of Liquid B. Hydrogen H2 gas is bubbled into each upside-down beaker until 100mL of liquid has been displaced. The masses mA and mB of hydrogen inside each beaker is then chemically determined. Note for advanced students: you may assume the solubility of H2 in either liquid is very low.
a. mx will be greater than my
b. mx will be less than my
c. mx will be equal to my
d. It's impossible to predict whether mx or my will be greater without more information.
Answer:
Mx will be less than My.
Explanation:
The correct option is - Mx will be less than My.
Because, liquid X have been higher viscosity and vapor pressure than liquid B.
Vapor pressure of liquid A is greater, so the amount of liquid X will vaporized greater and H2 gas has been displaced greater from the beaker as compared to liquid Y.
The amount of H2 in liquid Y remains greater in beaker as compared to liquid X.
So, Mx will be less than My.
If a compressed air cylinder for scuba diving contains 6.0 L of gas at 18°C and 200 atm pressure, what volume does the gas occupy at 1.0 atm and 25°C?
Answer:
[tex]V_2=1228.9L[/tex]
Explanation:
Hello there!
In this case, given the pressure, temperature and volume of the gas, we notice that we need the combined ideal gas as shown below:
[tex]\frac{P_2V_2}{T_2} =\frac{P_1V_1}{T_1}[/tex]
Thus, solving for the final volume, V2, we would obtain:
[tex]V_2=\frac{P_1V_1T_2}{T_1P_2}[/tex]
Now, we plug in the data and make sure the temperature must be in Kelvins to obtain:
[tex]V_2=\frac{200atm*6.0L*(25+273)K}{(18+273.15)K(1.0atm)}\\\\V_2=1228.9L[/tex]
Best regards!
A student is heating a crystal of alum to
determine the hydrate formula. If she removes
it from the heat before all the water has been
removed, what will happen to the calculated
hydrate formula?
A. It will not be affected by the error.
B. The mole ratio will indicate less water than was
actually present.
C. The mole ratio Will indicate less alum than was
actually present.
Help me! Who ever gets to answer and has the best answer gets brainliest
Answer:
Decay-the breakdown of dead plants..
Earth- thermal energy comes from deep inside...
Fires- these consume feul...
Explanation:
Answer:
Fires - These consume fuel and covert chemical energy stored in that fuel into thermal, light and sound energy
Decay - The breakdown of dead plants and animals produces thermal energy
Earth - Thermal energy comes from deep inside and is called geothermal energy
Explanation:
Fires, when you burn wood, you convert chemical energy from the wood into thermal (warmth from the fire), light (glow from the fire), sound (crackling sound of wood burning)
Decay - I can't explain that one to you but there are power plants that use decomposition to produce energy
Earth - Beneath the crust there is the mantle, which consists of molten rock which produces a lot of thermal energy. This can be seen in geysers, where the molten rock heats water and hot water can burst out of the surface. Applies to hot springs too
Which statement defines enzymatic activity? Enzymes are required to slow down biological reactions within cells. Specific enzymes can catalyze a wide variety of chemical reactions. Enzymes regulate cellular functions through feedback mechanisms. Enzymes bind substrates so that reactive groups have many different orientations.
Answer:
Enzymes are required to slow down biological reactions within cells,
this could be not sure
Answer:
D
Explanation:
Enzymes bind substrates so that reactive groups have many different orientations.
Help me! Who ever gets to answer and has the best answer gets brainliest (very easy!)
Answer:
Fires --> These consume fuel and convert chemical energy stored in that fuel into thermal light and sound energy.
Decay -->The breakdown of dead plants and animals releases thermal energy.
Earth --> Thermal energy comes from deep inside and it is called geothermal energy.
How do chemists count the number of representative particles in a substance?
Which describes bonding electrons in a polar covalent bond?
electrons that are not shared equally
electrons that are shared in diatomic molecules
electrons that are shared equally
Answer:
I think the third one
Explanation:
i think
Answer:
electrons that are NOT shared equally
Explanation:
.....plllzzz heeelp me fast??
Answer:
Explanation:
It is 11
A gas goes from 1L at 273 K to 2 L when heated. What is the new temp?
Answer:
Given : Diatomic molecule at 273K
'q' absorbed = positive = +100Cal = 100 x 4.184J = 418.4J
'W' done by system = negative = -209J
By first law of thermodynamics;
ΔU = q + W = 418.4 + (-209) = 209.4J
We know for diatomic molecule Cv=25R and CvΔT=ΔU
CvΔT=209.4
25RΔT=209.4
ΔT=5R209.4×2
And, Heat exchange=Cm×ΔT
where; Cm is molar heat capacity
Cm=ΔTHeat Exchange
substituting values for Heat Exchange = 418.4 and ΔT=5R209.4×2
Cm=5R
Formula mass of Ca(NO2)2
Answer: 132.1 g/mol
Explanation: 40.08 + 2·(14.01+2·16)
what is one property of skim milk indicating that it is a colloidal dispersion?
Answer:
it's dairy
Explanation
Calculate the pH of a 0.10 M NH4Cl solution.
Answer:
Answer: pH = 2.72
Explanation:
Calculate the pH of 0.010 M HNO2 solution. The K, for HNO2 is 4.6 x 104
29. Which is the electron configuration of an atom
in the excited state?
(1) 1s 2s²2p2
(2) 1s 2s22p'
(3) 1s 2s22p5352
(4) 1s²2s²2p%35'
What is the hydronium ion concentration of a solution whose pH is 4.12?
a. 5.1 x 10–6 M
b. 7.6 x 10–5 M
c. 6.4 x 10–5 M
d. 4.4 x 10–8 M
You have to prepare a pH 5.00 buffer, and you have the following 0.10 M solutions available: HCOOH (pka=3.74), HCOONa, CH3COOH (pka=4.74), CH3COONa, HCN (pka=9.31), and NaCN. Which solutions would you use?
Answer:
CH3COOH - CH3COONa since its pKa is closest to the required pH.
Explanation:
Hello there!
In this case, in agreement with the theory of buffers as solutions able to withstand severe pH changes due to the addition of acidic or basic substances, it is possible to set up a generation equilibrium expression for the acids herein given:
[tex]Ka=\frac{[A^-][H_3O^+]}{[HA]}[/tex]
Which leads to the Henderson-Hasselbach equation:
[tex]pH=pKa+log(\frac{[A^-]}{[HA]} )[/tex]
Thus, since all the buffers have [A-]=[HA]=0.10M, the log part becomes 0 and therefore the best buffer will have the closest pKa to the required pH, which is CH3COOH - CH3COONa since its pKa is 4.74.
Best regards!
[tex]CH_3COOH\; and\; CH_3COONa[/tex] can be used to prepare a pH buffer, if 0.10 M solution available of the solutions.
What is buffer?Buffer is a solution, that resist change in pH, by adding or removing H+ ions to the solution.
Maintaining a constant pH is necessary to complete many reactions.
In blood, bicarbonates maintain the pH of the body.
[tex]CH_3COOH\; and\; CH_3COONa[/tex] have approx the nearest pH, so they can be used to make a buffer.
Thus, the correct options are [tex]CH_3COOH\; and\; CH_3COONa[/tex]
Learn more about buffer
https://brainly.com/question/24188850
In what form metals are found in nature
Answer:
Metals in nature are found in rock form, mineral forms etc..
Answer:
Metals are found in rock
The gases are contained in a reaction vessel and are in equilibrium at 298 K
X2Zi â 2XZ2(g)
a. Activation energy
b. Total mass of the system
c. Molar concentration of XZ4(g)
d. Number of molecules present
e. Equilibrium constant
1. Is decreased by the addition of a catalyst?
2. Is decreased when the volume of the reaction vessel is increased and equilibrium is reestablished at 298 K?
Answer:
1) Activation energy ( A )
2) Molar concentration of X[tex]_{2}[/tex]Z[tex]_{4}[/tex](g) ( C )
Explanation:
X[tex]_{2}[/tex]Z[tex]_{4}[/tex](g) ⇄ 2XZ
1) Activation energy Is decreased by the addition of a catalyst
while Equilibrium constant will Increase and other options will still remain unaffected
2)Molar concentration of X[tex]_{2}[/tex]Z[tex]_{4}[/tex](g) Is deceased when the volume of the reaction vessel is increased and equilibrium is reestablished at 298 K
while Number of molecules present will Increase
What is mass times acceleration equal to?
Answer:
Mass (kg) × Acceleration (m/s²) = Force (N)