A student mixes two chemicals in a test tube. She notices that the mixture starts to bubble and the test
tube feels very warm. The student most likely concludes that the mixture is-
F. a chemical reaction that happened too quickly.
G. an endothermic reaction that absorbed thermal energy.
H. an exothermic reaction that released thermal energy.
J. not a chemical reaction.
Answer:
H. an exothermic reaction that released thermal energy.
Explanation:
The student will most conclude that this is a chemical reaction in which thermal energy is released to the environment.
Such reactions accompanied by the release of thermal energy are exothermic reactions.
In an exothermic change, heat is liberated to the surrounding. The surrounding becomes hotter at the end of the changes. For such reaction we say that enthalpy change is negative.For endothermic reactions, heat is absorbed. At the end of the reaction, the system is cold.
3 The weight of an atom is determined primarily by —
A) the total number of protons plus neutrons
B) the total number of protons plus electrons
C) the total number of neutrons plus electrons
D) the total number of electrons, protons, and neutrons
Answer:
A)The total number of protons plus neutrons= Weight of an atom
In a water molecule (H2O), the oxygen atom has two unshared pairs of electrons and two bonding pairs of electrons. How do the unshared pairs affect the bond angle?
Answer:
They reduce the bond angle to be slightly lower than the tetrahedral bond angle, approximately 104.45 degrees.
Explanation:
The unshared pair of electrons or lone pair electrons in order to have the minimum repulsion possible with each other pushes the other bonding pairs closer together making the bond angle smaller or bent.
The bond angle is slightly lower than the tetrahedral bond angle of 108 degrees, leaving the water molecule with a bent molecular geometry.
For questions 14-16 pick out the variables that will be needed to answer the following question: Do trees grow faster if it is wetter in the summer?
14) What is the independent variable?
a.) amount of rain
b.) no rainfall
c.) amount of growth
15) What is the dependent variable?
a.) amount of rain
b.) no rainfall
c.) amount of growth
16) What is the control?
a.) amount of rain
b.) no rainfall
c.) amount of growth
Answer:
14) A. amount of rain
15) C. amount of growth
16) B. no rainfall
Explanation:
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Calculate normality and tire of KOH solution , if CN H2 C2 O4 solution , that is nessesary for titration is 0.1050 mol/1 and the Volume is 5.0 ml ; the volume of KOH - solution is 4.5 ml
Answer:
Normality of KOH = 0.1062 N
Note: The given question is not clearly stated. A related question below is answered and explained;
What is the NORMALITY of a solution of KOH if 45.18 mL are required to neutralize 0.3g of pure oxalic acid H2C2O4 . 2H2O?
Explanation:
Equation of the reaction: 2KOH + H₂C₂O₄.2H₂O --> K₂C₂O₄ + 4H₂O
molar mass 0f KOH = 56 g/mol; molar mass of H₂C₂O₄.2H₂O = 126 g/mol
Number of moles of in 0.3 g of H₂C₂O₄.2H₂O = mass/molar mass
number of moles = 0.3 g / 126 g/mol = 0.0024 moles
From the equation of reaction, 2 moles of KOH are required to neutralize 1 mole of H₂C₂O₄.2H₂O
Number of moles of KOH required to neutralize 0.0024 moles of H₂C₂O₄.2H₂O = 2 * 0.0024 = 0.0048 moles
Molar concentration of 45.18 mL solution of KOH containing 0.0048 moles of KOH = number of moles/volume (L)
molarity of KOH solution = (0.0048/45.18 mL) * (1000 mL/1 L) = 0.1062 mol/L
Normality = n * molarity
where is the number of moles of OH⁻ ions produces from mole of KOH = 1
Normality of KOH = 1 * 0.1062
Normality of KOH = 0.1062 N
What variable represents specific heat in the equation Q = mcAT?
O A. The variable c
OB. The variable T
O C. The variable m
O D. The variable Q
Answer: A. The variable c
============================================
Explanation:
Q = heat transferred
m = mass
c = specific heat
[tex]\Delta T[/tex] = delta T = change in temperature
Oil and water placed in a jar will separate. Even when shaken and mixed, the oil still separates from the water.
Which best describes oil and water?
Oil and water are highly soluble because they have separate chemical properties.
Oil and water have a low solubility because they have separate chemical properties.
Oil and water are highly soluble because they exert different pressures.
Oil and water have a low solubility because they exert different pressures.
Answer:
Probably B?
Explanation:
I don't have one...
Hope it helps I guess..
Answer: i think is B
Explanation: HATE ME IF IM WRONG
*
When Gallium becomes an ion it loses 3 electrons to become:
A: -3
B: +3
C: It loses 3 electrons to become a neutral atom
D: It is already neutral
Answer:
B: +3
Explanation:
If Gallium loses 3 electrons, it will become an ion.
The ion will be positively charged because in this new ion, the number of electrons is lesser than the number of protons. The charge difference will impart a positive net charge on the ion.
In a neutral atom, the number of electrons and protons are the same. For positively charged ions, the number of protons is greater than the electronsIf Gallium the loss of 3 electrons offsets the charge balance in the chemical specie. Thus, the ion will have a net +3 charge.
Does the following equation follow the law of conservation of mass? Show your work
AgNO3 → Ag2 + NO3
Answer:
No.
Explanation:
If the equation follows the law of conservation of mass, then the amount of reactants must be equal to the amount of products. That is not the case for the provided equation due to 1 Ag on the reactants side versus 2 Ag on the products side.
What signs of a chemical reaction did you observe during the lab? Check all that apply.
color change
temperature change
mass change
formation of a gas
formation of a solid
formation of a liquid
Answer:
1, 4, 5
Explanation:
1 - Color Change
4 - Formation of Gas
5 - Formation of Solid
(correct on ed)
Answer: A, D , E
Explanation:
13. What is the frequency of a wave that has a wavelength of 2.73 x 10-7m?
Answer:
f = 1.09 × 10¹⁵ Hz
Explanation:
Given data:
Frequency of wave = ?
Wavelength of wave = 2.73 ×10⁻⁷ m
Solution:
Formula:
Speed of light = frequency × wavelength
speed of light = 3× 10⁸ m/s
by putting values,
3× 10⁸ m/s = f × 2.73 ×10⁻⁷ m
f = 3× 10⁸ m/s / 2.73 ×10⁻⁷ m
f = 1.09 × 10¹⁵s⁻¹
s⁻¹ = Hz
f = 1.09 × 10¹⁵ Hz
Word equation of almininum reaction with oxygen
Answer:
Aluminium + oxygen = almininum oxide
Hope it helps!! Please make me brainliest...
Merry Christmas good day
___C + ___S8 → ___CS2
Answer:
4,1,4
Explanation:
Balancing a synthesis equation
What is the chemical equation for photosynthesis?
A. carbon dioxide + water + glucose yields sunlight + oxygen
B. glucose + oxygen + water yields carbon dioxide + helium + light energy
C. carbon dioxide + oxygen yields light energy + water
D. carbon dioxide + water + light energy yields glucose + oxygen
Answer:
D.
Explanation:
This is the correct equation for photosynthesis! :)
How many grams of NaCl would be required
to react with 346 mL of 0.607 M AgNO3
solution?
Answer:
Mass = 12.27 g
Explanation:
Given data:
Mass of NaCl are required = ?
Volume of AgNO₃ = 346 mL (346 mL× 1L/ 1000 mL = 0.346 L)
Molarity of AgNO₃ = 0.607 M
Solution:
Chemical equation:
NaCl + AgNO₃ → NaNO₃ + AgCl
Number of moles of AgNO₃:
Molarity = number of moles / volume in L
0.607 M = number of moles / 0.346 L
number of moles = 0.607 M × 0.346 L
number of moles = 0.21 mol
now we will compare the moles of NaCl and AgNO₃.
AgNO₃ : NaCl
1 : 1
0.21 : 0.21
Mass of NaCl:
Mass = number of moles × molar mass
Mass = 0.21 mol × 58.44 g/mol
Mass = 12.27 g
Consider the reaction: 2AB2 → A2 + 2B2 You start with one mole of AB2 and the reaction is done at constant pressure of 3.7 atm and 28.2 °C. Assume all gases behave like ideal gases. What is the value of the work (in J)?
Answer:
-2503.2J
Explanation:
At constant pressure, change in work follows the equation:
W = -P*ΔV
Where W is work, P is pressure (3.7atm) and ΔV is change in volume
We can obtain change in volume using ideal gas low:
ΔV = ΔnRT/P
Where Δn is change in moles (3moles of products - 2 moles of reactants = 1)
R is gas constant (0.082atmL/molK)
T is absolute temperature (28.2°C + 273.15 = 301.35K)
P is pressure (3.7atm)
ΔV = ΔnRT/P
ΔV = 1mol*0.082atmL/molK*301.35K/3.7atm
ΔV = 6.69L
And work is:
W = -3.7atm*6.69L
W = -24.71atmL
1atmL = 101.3J
-24.71atmL * (101.3J / 1atmL) =
-2503.2J
I forgot, please help!
What object do you think will take up
more space? Why do you think this?
Answer:
solids
Explanation:
BC they r heavier than liquid and gas
What is mole concept? how to do its numericals
How many grams of water would require 2250 joules of heat to raise it’s temperature from 34.0 C to 100.0 C ?
Answer:
8.117grams
Explanation:
its obtained from Q=MCT where
Q-HEAT REQUIRED
C-SPECIFIC HEAT CAPACITY OF WATER
M-MASS OF WATER
T-TEMPERATURE CHANGE(100C-34C)
3. True or False: White light is a mixture of all colors of the visible
spectrum.
O True
False
it's true ....
plz mark my answer as brainlist plzzzz vote me also
Which substance below has the greatest intermolecular forces?
O oxygen with a boiling point of -183°C
O water with a boiling point of 100°C
O gold with a boiling point of 2,970°C
O mercury with a boiling point of 357°C
Answer:
Oxygen with a boiling point of -183°C.
Explanation:
Higher the intermolecular forces between the liquid particles, more durable it's for it to flee into the vapor part,you would like a lot of energy to convert it from liquid to the vapor part, in different words, higher its boiling point.
Hope it helps!<3
HELP PLSSS FASTTTTTT!!!!!!!!!!!!!!!!
Answer:
with what?
Explanation:
What is the percent composition by mass for hydrogen in water (H2O)?
% H =(_____/_____)x100%=______ % H
Explanation:
Percentage composition = 2/18 = 11.11%.
5. Calculate the time required to deposit 0.37g of Silver from a silverNitrate solution using a current of 2.5A( Charge of Ag in AgNO3 is + 1)
Time required : 132.2 s
Further explanationGiven
mass of Silver = 0.37 g
current = 2.5 A
Required
time do deposit
Solution
Faraday's Law :
[tex]\tt W=\dfrac{e.i.t}{96500}[/tex]
e = ar/valence (valence Ag = 1)
i = current
t = time = s
[tex]\tt 0.37~g=\dfrac{108/1\times 2.5~A\times t }{96500}\\\\t=132.2~s[/tex]
Calculate: (5.03 x 109) – (42.6 x 108) =
Answer: x108(5.03x−42.6)
Explanation: Factor 5.03x109−42.6x108
5.03x109−42.6x108
=x108(5.03x−42.6)
help me please... tyy if you do :))
Answer:
a) HCl
Explanation:
As we know, that HCl or Hydrogen Chloride is a diatomic compound. It is formed due to the Chemical reaction of Hydrogen and Chlorine. As both Hydrogen and Chlorine have valencies of 1, the Net Valency of the Compound HCl is 1 itself. This separates it from the rest of the compounds. The rest of the compounds need to have more than 2 atoms of each kind and have different valencies too.
Which statement best describes what would happen to an ecosystem once the sun is removed?
A. The functions within the ecosystem will eventually stop & everything will die off.
B. The ecosystem will continue to thrive; it does not need the sun's energy to work.
C. The ecosystem will look for a different source of energy to use.
D. The ecosystem will instantly stop working.
Answer:
A. The functions within the ecosystem will eventually stop & everything will die off.
Explanation:
Everything is dependent on the sun --starting from the bottom of the food chain, the producers. However, we wouldn't die instantly because "Earth retains heat fairly well, so humans wouldn't freeze instantly."
If you have 9.0x10^24 molecules of water, how many moles of water do you have?
Answer:
14.9 moles of water
Explanation:
Given data:
Number of molecules of water = 9.0×10²⁴ molecules
Number of moles of water = ?
Solution:
Avogadro number:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
1 mole = 6.022 × 10²³ molecules of water
9.0×10²⁴ molecules ×1 mol / 6.022 × 10²³ molecules
1.49×10¹ moles
14.9 moles
Describe are seasons like near the equator.
Answer:
Hi! Think of it like this:
You and your family are going to go on a vaction for the holidays, to south america or somewhere else. You´re near the equator so it will be warm. If you were to move there, you might pull out the swimsiutes because most of the time, its useally warm and sunny. They dont really get cold weather. They will have a nice and warm christmas.