The reaction is endothermic because the temperature dropped from 28 degrees Celsius to 20 degrees Celsius.
Meaning of endothermic and exothermic reaction:An endothermic reaction is one in which heat is absorbed from the surrounding resulting in decrease in temperature while an exothermic reaction is one in which heat is evolved causing the temperature to rise.
In the particular context of this question, the reaction is endothermic because the temperature dropped from 28 degrees Celsius to 20 degrees Celsius. The heat in the surroundings decreased.
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Mercury is an environmental pollutant that is produced by the burning of
fossil fuels and can be toxic to wildlife and humans. What does this show
about the impact of chemicals on the environment?
A. The harm chemicals could have on the environment outweighs the
benefits that people get from the chemicals.
B. People cannot control the negative effects of chemicals on the
environment.
C. All chemicals that people introduce into the environment are
harmful.
D. The beneficial effects people get from chemicals may have
unintended harmful effects on the environment,
Pls help if you only know the correct answer! Thanks!!
Answer:
1. H=2, O=1
2. H=4, O=2
3. C=1, O=1
4.
a. reactants C=1, O=2
b. products C=1, O=2
5.
a. reactants H=4, O=2
b. products H=4, O=2
6
a. reactants C=1, O=1, H=4
b. products C=1, O=1, H=4
The atomic mall mass is an element depends upon the.
Answer:
Mass and relative abundance of each isotope of that element
The atomic mass of element has been dependent on mass of each isotopes and their abundance in nature.
The atomic mass has been the mass of neutrons and protons of the element. There has been the presence of the isotopes of the elements, with varying abundance, and varying atomic masses.
The atomic mass of the element has been the relative average atomic mass of the element with respect to the mass of the isotopes and their percent abundance.
The average atomic mass (amu) has been given by:
[tex]amu=M_1A_1\;+\;M_2A_2[/tex]
Where, [tex]M_1A_1[/tex] has been the atomic mass and abundance of isotope 1.
[tex]M_2A_2[/tex] has been the atomic mass and abundance of isotope 2.
Thus, the average atomic mass has been dependent on mass of each isotopes and their abundance in nature.
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what should you do if your bunsen burner does not light after a few tries with the striker?
What causes an echo?
refraction
rarefaction
reflection
please help
Tell me What is an element?
Answer:
Any substance that cannot be decomposed into simpler substances by ordinary chemical processes.
Another definition:
An element is the simplest pure substance which can neither be split nor built up from other simpler substances by chemical reaction
significance of symbol Mg
Answer:
Magnesium Magnesium is used in products that benefit from being lightweight, such as car seats, luggage, laptops, cameras and power tools. It is also added to molten iron and steel to remove sulfur. As magnesium ignites easily in air and burns with a bright light, it's used in flares, fireworks and sparklers.I hope this helps you !!PLEASE HELP!!!
ILL MARK AS BRAINIEST AND GIVE YOU 30 POINTS!!!
Answer:
did u get it yet
Explanation:
If the energy of the H–H bond is 452 kJ/mol. The energy of the O=O bond is 598 kJ/mol. The energy of the O–H bond is 367 kJ/mol, which bond would be the strongest? Which bond would be the weakest?
Taking into account the bond energy, the O=O bond is the strongest and the O–H bond is the weakest.
The bond energy is the average total energy that would be released by the formation of a mole of chemical bonds, from their constituent fragments (all in the gaseous state).
In other words, the normal or standard bond enthalpy is defined as the change in enthalpy or heat released, under standard conditions of 1 atmosphere and 25ºC, that accompanies the reaction of formation of one mole of bonds from the isolated atoms in gaseous state.
The higher the bond energy, the stronger and more stable the bond will be.
So, taking into account all the previous, the O=O bond is the strongest and the O–H bond is the weakest.
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Answer:
valence electrons get closer but rest of them are remain same
True or false: The
louder you yell into a
megaphone in space,
the more likely it is for
the sound waves to
travel.
Answer:
True
Explanation:
This is known as a lapse rate. When you shout something to someone across the lake, the sound waves near the surface end up moving faster than the sound waves higher up. Since the speed is greatest near the ground, sound waves bend upward, causing the audio to be just out of ears reach.
Two students are exploring a creek in their neighborhood.
The students hope to find some fossils along the way. What kinds of rocks should the students look for on their hike, and why should they look for those kinds of rock?
What is the chemical reaction by which organisms break down food
molecules for energy?
Answer:
cellular respiration
Explanation:
hope this helps :)
brainliest plzzzzzzz
Which property determines whether a substance is a solid or liquid at room temperature?
Answer:
1. The kinetic energies of the particles (atoms, molecules, or ions) that make up a substance. Kinetic energy tends to keep the particles moving apart.
2. The attractive intermolecular forces between particles that tend to draw the particles together.
as the atoms of the elements from atomic number 3 to 9 are considered in sequence from left to right on the periodic table, the atomic radius of each successive atom is
Answer:
decreasing
Explanation:
from left to right the nuclear effective charge is increasing, attracting with a greater force the electrons and making the atom to reduces itd atomic radius
The atomic radius decreases along a period in periodic table. Thus, from the third element Li to the 9th element fluorine, atomic radius decreases and F has the lowest radius among them.
What is atomic radius?Atomic radius is the distance from the nucleus to the valence shell. The atomic radius decreases from left to right in periodic table. Thus, the higher atomic radius is exhibited by metallic elements.
The horizontal rows in the periodic table is called periods. Along a period , atomic radius decreases and electronegativity increases. When moving to the right there is no increase in the number of shells and the filling of electrons does not achieve octet except for group 18. Hence, they are electronegative.
From atomic number 3 to 9 atomic number is decreasing. Hence, among these elements, the smallest one is fluorine (Z = 9).
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most common elements that bond with oxygen
Explanation:
most common elements that bond with oxygen is Hydrogen (H2) to form water
Pls help if you only know the correct answer! Thanks! :)
Answer:
i think itd be an exothermic reaction
Explanation:
An exothermic process releases heat, causing the temperature of the immediate surroundings to rise.
two step mole conversions, giving brainliest
Answer:
Our process will be to change the mass of NO2 to moles by dividing by the molar mass, and then we multiply the number of moles with Avogadro's number (6.02 x 10^23)
Molar mass of NO2 = (14) + (16)x2 = 46g/mol
45.8/46 = 0.99 or just 1 mole when you round it.
Now just multiply the moles with Avogadro's number
1 x (6.02 x 10^23)
= 6.02 x 10^23 molecules of NO2 reside in 45.8g of NO2
perform the converters
a) 32gr C2H4-in liters
b) 7,5 litera N2- in molecules
c) 1.4•10 ² ³ molecules CH4- in atoms
Answer:
the answers are given in the photo
What happens to the molecules of a gas when the gas is heated?
A.
The gas becomes a liquid.
B.
The molecules collide less frequently.
C.
No change occurs with regard to the molecules.
D.
The average speed of the molecules increases.
Answer:
the correct answer is D because the heat causes the molecules to speed up
in three to five sentences, predict the bonding activity between phosphorus and chlorine. why do you think they would bond that way?
The bonding activity that occurs between phosphorus and chlorine is Covalent Bonding
Covalent bonding is an interaction between two atomic elements that share electrons between themselves.
In Phosphorus Pentachlorine PCl₅, covalent bonding occurs between Phosphorus and Chlorine.
This is because, Phosphorus is the central atom that is attached to 5 different chlorine atoms, each chlorine atom needs one electron each to complete its octet rule and since phosphorus has five valence electrons in its outermost shell, it shares it with each of the chlorine atoms.
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Answer:
Covalent Bonding
4. Which of the following statements accurately compares the wavelengths of the waves shown below?
A) wave 1 has a smaller wavelength than wave 2
B) wave 1 has a larger wavelength than wave 2
C) wave 2 has a larger wavelength than wave 1
D) wave 1 and wave 2 have the same wavelength
Answer:
B. wave 1 has a larger wavelength than wave 2
Wave 1 has larger wavelength than wave 2. Hence, option B is correct.
What is Wavelength?Wavelength is defined as "the difference between two successive crests and troughs of the wave. The wavelength described the how long wave is. It is measure in the direction of wave.
Wavelength is usually denoted by the Greek letter ( λ ).
Wavelength is equal to the speed ( V ) of wave train to divided by frequency ( F ). It is given as,
λ = V ÷ F
Here,
λ = wavelength
V = speed
F = frequency
The distance between one crests (top) to another crests is a Wavelength. Alternately the distance between one troughs (bottom) to another troughs is wavelength.
The distance between two crests in wave 1 is more comparatively wave 2 so , wave 1 will have larger wavelength than wave 2.
Therefore, wavelength is used for measuring the radiation.
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What is the enthalpy of reaction for the decomposition of calcium carbonate? CaCO3(s) Right arrow. CaO(s) CO2(g) kJ.
The enthalpy of reaction for the decomposition of calcium carbonate is 177.4 KJ/mole .
We know that the enthalpy of reaction can be obtained from the enthalpy of formation of the reactants and that of the products using the formula;
ΔHrxn = ΔHf (products) - ΔHf (reactants)
The heat of formation of the species are as follows;
ΔHf (CaCO3(s)) = −1206.9 KJ/mol
ΔHf (CaO(s)) = - 636 KJ/mole
ΔHf (CO2(g)) = -393.5 KJ/mole
ΔHrxn = [( -393.5 KJ/mole ) + ( - 636 KJ/mole)] - [ −1206.9 KJ/mol]
ΔHrxn = 177.4 KJ/mole
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Answer:
First one is 656.3 and second is endothermic.
Explanation:
Edge Thermochemical Equations assignment
You are studying the boiling points of liquids with some fellow students. You have two liquids of different molecular weights, and you test each of them twice. You find that the one with a lower molecular weight also has a lower boiling point. You would like to be more confident with the pattern you are noticing. What are two possible next steps? In one to two sentences, give specific, different examples of how the experiment could be extended, assessed, or improved.
The boiling points of two or three other pairs of liquids in which one liquid has a lower molecular mass than the other can be studied in order to see if the pattern is consistent.
The boiling point of a substance refers to the temperature at which its vapor pressure is equal to the atmospheric pressure. The boiling point of a substance has a lot to do with its molecular mass.
Generally, substances that has a higher molecular mass has a higher boiling point except other factors at at work. In order to confirm whether the pattern that you are noticing about molecular weights and boiling point is consistent, three other liquids with different molecular masses, one being higher than the other can be studied and their boiling points compared.
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A 24.81-g sample of a gaseous compound containing only carbon, oxygen, and chlorine is determined to contain 3.01 g C, 4.00 g O, and 17.81
g Cl. What is this compound's percent composition?
Explanation:
getting the empirical formula
For carbon
3.01/12 = 0.2508
For oxygen
4/16 = 0.25
For Cl
17.81/35.5= 0.501
0.2508 ÷ 0.25 = 1.0032
0.25 ÷ 0.25 = 1
0.501 ÷ 0.25 = 2.004
Empirical formula of the compound = CCl20
Molar mass = (1×12) + (2×35.5) + (1×16)
= 12 + 71 + 16
= 99g/mol
percentage composition= 24.81/99 × 100
= 25.06%
A 24.81-g sample of a gaseous compound containing only carbon, oxygen, and chlorine is determined to contain 3.01 g C, 4.00 g O, and 17.81 g Cl. the compound's percent composition is 25.06%.
What are the application of carbon ?The impure form of carbon is Amorphous which is used for the manufacture of car batteries and dry cells, ink and paints; So the majority element of carbon is present in charcoal, so these are used as fuel.
Graphite is derivative form of carbon used as a lubricant in heavy industrial machinery, making pencil leads, these carbon are used in the production of steel.
The empirical formula, For carbon 3.01/12 = 0.2508
For oxygen 4/16 = 0.25, For Cl 17.81/35.5= 0.501, 0.2508 ÷ 0.25 = 1.0032
0.25 ÷ 0.25 = 1
0.501 ÷ 0.25 = 2.004
Empirical formula of the compound = CCl20
Then the Molar mass = (1×12) + (2×35.5) + (1×16)
= 12 + 71 + 16
= 99g/mol
percentage composition= 24.81/99 × 100
= 25.06%
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why is it impossible to have an undiscovered element that would fit between sodium and magnesuim
Answer:
Sodium has 11 protons and Magnesium has 12. The way that the periodic table is set up doesn't allow for any elements to be in between. The element would have to have 11.5 protons, which is impossible
Structure of periodic table is designed in a way that successive elements have difference of 1 electron and proton as sodium and magnesium have 11 and 12 protons respectively there is no space for any other element.
What is periodic table?Periodic table is a tabular arrangement of elements in the form of a table. In the periodic table, elements are arranged according to the modern periodic law which states that the properties of elements are a periodic function of their atomic numbers.
It is called as periodic because properties repeat after regular intervals of atomic numbers . It is a tabular arrangement consisting of seven horizontal rows called periods and eighteen vertical columns called groups.
Elements present in the same group have same number of valence electrons and hence have similar properties while elements present in the same period show gradual variation in properties due to addition of one electron for each successive element in a period.
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Look at the diagram. Which shows the correct arrangement of electrons in a hydrogen chloride molecule?
Answer:
D............................
There are two types of chemical compound one is covalent compound and another is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. The correct representation is option D.
What is chemical Compound?Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.
Covalent bond is present in molecule HCl. Hydrogen has 1 electron in its outermost shell. Chlorine has 7 electrons in its valence shell. So one one electron from each element is shared between them to form a covalent bond.
Therefore, the correct representation of arrangement of electrons in a hydrogen chloride molecule is option D.
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How many molecules are in 0.750 moles of magnesium sulfide?
Answer:
4.51 x 10 to the 23 power
Explanation:
what was johann dobereiner contribution to the periodic table
Answer:
he introduced triads of similar chemical properties in periodic table.
Explanation:
Anyone down to start a convo