The heat of combustion of the sample is calculated to be -1300 kJmol-1.
We know that energy is neither created nor destroyed but is converted from one form to another. The heat lost by the ethanol when it is burnt is equal to the heat gained by the calorimeter.
Heat gained by calorimeter = 2.×10^3 g × 2. 45 Jg-1°C-1 × 1. 33°C
= 6.5 kJ
Number of moles of ethanol = 0. 2301 g/46 g/mol = 0.005 moles
Heat of combustion of the sample = -( 6.5/0.005 moles) = -1300 kJmol-1
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the idea of arranging the elements in the periodic table
Elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass. The rows are called periods.
Why is there a large difference between day and night temperatures in a desert?
All rainfall in a desert happens at night.
There are no plants to trap the heat.
Heat escapes rapidly at night because the air is so dry.
The ground absorbs all heat. 20 points :,)
Answer: Heat escapes rapidly at night because the air is so dry.
Explanation: The desert has little humidity and rarely is cloudy. These two factors allow the desert to heat up rapidly during the day and cool off quickly at night.
New research shows that a red food colouring with an R value of 0.62 (when a particular solvent and temperature are used) could be dangerous to certain people. Samples of food colouring from two different red sweets were collected and the chromatogram bolow was produced. For each of the sweets, state and explain whether or not you would recommend that the sweets are taken off the market based on this research,
It is recommended only for the second type of candy to be taken off the market.
Based on the background information, if a candy shows a 0,62 Rf value in the chromatography it is considered potentially dangerous, and therefore it should be taken off the market.
The Rf value is calculated using the following formula:
Rf = Total distance traveled by a component/ Total distance from the pencil line to the solvent frontNow, let's find out if any of the components has an Rf equal to 0,62.
Note: To determine the distances I measured the image using a ruler and you can do the same, this will not alter the results.
Sample 1Total distance traveled by the component: 6cmTotal distance: 7 cmRf : 6 cm/ 7 cm = 0.852. Sample 2
Total distance traveled by the component: 4.34cmTotal distance: 7 cmRf : 4.34 cm/ 7 cm = 0.62This means sample 2 has the 0.62 Rf value and therefore it needs to be taken off the market.
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Enter the correct ground-state (or lowest energy) configuration based on the number of electrons: 1s^2 2p^6 3s^2.
Answer:
The ground state represents the lowest-energy state of the atom.
Explanation:
sd
Match each term in the first column with an example in the second column. On a sheet of paper, write the letter of the answer.
1. physical property
2. chemical property
A ability to burn
3. solid
4. liquid
B rust appears on a nail C a puddle freezes
5. physical change
6. chemical change
D substance that has a definite shape and volume
E temperature or density
F substance that has a definite volume, but no definite shape
Answer:
wait can you go more in detail i can help you because i dont understand whats going on
What is the relationship between plants soil and fertilizers?
what is the chemical formula of tetraphosphorus heptasulfide?
Answer: P4S7
Explanation:
elements of the fourth period fill the 4s sublevel with electrons before filling the 3d sublevel. Also, some elements move an electron from a filled 4s sublevel to an unoccupied 3d sublevel. Explain these behaviors
Answer:
Elements fill the lowest energy subshells first(Aufbau's rule), and the 4s subshell is lower energy than the 3d, making the labeling deceiving. In some rare situations, the electrons would rather have Hund's rule be respected more, having all electrons facing one way with no doubled up because it is more stable(these are pretty rare and usually deal with transition metals like copper).
Hope this helps!
Explanation:
As it has less energy than the 3d orbital, the 4s orbital fills next. Following the filling of the electrons, 4s has more energy than 3d. Therefore, the two electrons in the 4s are at a higher energy than they could be in the 3d since it has a vacancy. As a result, electrons transition from a higher to a lower energy orbital.
What are electrons ?The elementary electric charge of the electron is a negative one, making it a subatomic particle. Due to their lack of components or substructure, electrons, which are part of the lepton particle family's first generation, are typically regarded to be elementary particles.
Since 4s electrons are bound by the nucleus farther away and more loosely than 3d electrons, 4s electrons are eliminated first rather than 3d electrons.
The 4s orbital should always be filled before the 3d orbitals, according to the Aufbau principle, although this isn't the case for the majority of elements. After Sc, electrons actually enter the 3d orbitals first because they have a lower energy than the 4s orbital.
Thus, electrons transition from a higher to a lower energy orbital.
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HELP!!!!! I WILL GIVE BRAINLYEST write a 250 word report on a extinct or endangered animal
Answer:
bro thats plagiarism
Explanation:
As the ionic compound increases in
complexity, the melting point
A. increases
B. decreases
C. stays the same
Given what we know, we can confirm that as an ionic compound grows more complex, its melting point will increase.
What is an Ionic compound?An ionic compound is one in which atoms of elements share electrons between them to form compounds.These shared electrons generate powerful electrostatic forces that we refer to as ionic bonds. Electrostatic forces cause an increase in the melting point of a compound. As a compound grows more complex and adds more elements to its composition, it will gain new electrostatic forces, and thus increase its melting point.Therefore, as an ionic compound grows more complex, its melting point will increase due to the increasing number of strong electrostatic forces present in the compound.
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Answer: it INCREASES
if you don’t wanna read that long answer the other person put
Explanation:
An atom's electron configuration ends with 3p4. If another atom has seven more electrons, what would be the continuation of the electron configuration?
The continuation of the electron configuration would be [tex]3p^6, 4S^2, 3d^3[/tex].
The initial p orbital is partially filled. Hence, it has to be completely filled first in order to obey the orbital filling rule. Lower energy orbitals are first filled before higher energy orbitals.
After filling the p orbital with 2 electrons from the remaining 7 electrons, higher energy orbital 4s and 3d can then be filled.
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Answer:
3p^6 4s^2 3d^3
Explanation:
Compare the structure and bonding of the three compounds:
• carbon dioxide
•magnugum ondo
•silicon dioxide
(6 mark question)
Silicon dioxide is a covalent network solid. Magnesium oxide is an ionic compound while carbon dioxide is a covalent molecule.
Carbon dioxide is a covalent compound. The compound contains polar C-O bonds but overall the compound is nonpolar as such the molecules are held together by only weak dispersion forces.
The compound magnesium oxide is an ionic solid. It is composed of magnesium ions and oxygen ions in a crystal lattice. Owing to the fact that the ions are very small, the lattice energy is large and the compound is almost insoluble in water.
Silicon dioxide is a covalent network solid which is composed of chains of silicon - oxygen bonds. The network solid forms a very rigid structure having a high melting point.
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if you mix calcium hydrogen and carbon how many compounds will you have?
Answer:
Calcium monohydride is a molecule composed of calcium and hydrogen with formula CaH. It can be found in stars as a gas formed when calcium atoms are present with hydrogen atoms.Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen and calcium.
Explanation:
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What type of volcano is formed at a weak spot in the middle of a plate?
a.
lava
c.
hot spot
b.
fault
d.
plate
Hot spot volcano is the type of volcano which is formed at a weak spot in
the middle of a plate.
Hot spot volcano is an area in the Earth crust which is characterized by large
amount of heat flow in the area due to the volcanic activity. Hot spot
volcano is formed at the middle of the plate as against junctures in which
other types are formed.
The weak spot is what gives rise to the unusual heat flow which makes hot
spot volcano most appropriate.
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All three types of rock form in which earth layer?
Answer:
Lithosphere
Explanation:
All three types of rock make up the Earth's lithosphere, the outermost layer. The lithosphere averages about 100 kilometers in thickness.
How many moles of aluminum are needed to react completely with 2.1 moles of FeO? 2Al(s) + 3FeO(s) 3Fe(s) + Al2O3(s)
Answer:
1,4 mol
Explanation:
2 mol of Al reacts with 3 mol of FeO so for 2.1 mol of FeO you need 2 x 2.1 / 3 = 1.4mol
What is the total amount of work done when Danny lifted 25 pounds of weight over 5 meters and applying 30- Newtons of Force?
Answer:
Definition and Mathematics of Work
Calculating the Amount of Work Done by Forces
Potential Energy
Kinetic Energy
Mechanical Energy
what is the chemical formula for Salt and hydrogen gas?
What is a mixture ?
How do homogeneous & heterogeneous mixtures differ ?
1st question: A mixture is when the components of a mixture can be easily separated and that the components each keep their original properties.
2nd question:A phase is any part of a sample that has a uniform composition and properties.By definition, a pure substance or a homogeneous mixture consists of a single phase. A heterogeneous mixture consists of two or more phases. When oil and water are combined, they do not mix evenly, but instead form two separate layers.
Heterogeneous mixtures are not uniform in composition. Examples would be wood or blood. Homogeneous mixtures are uniform through out. Typically you can see through them.
What is the mass of 3.2 L of water in centigrams?
In water is the mass of one molecule equal to the mass of one molecule in steam
Answer:
The mass of one mole of water molecule = 18 ×N
A amu
Explanation: The mass of one mole of water molecule = Mass of one molecule ×N A Also mass of one mole of water is its molar mass in grams. So the mass of one mole of water is 18 g
magine that you are a water molecule in a group of many water molecules. Write a letter to a friend telling them about your journey through the water cycle on Earth. You can begin your journey anywhere you’d like, but you must complete an entire cycle and end the journey where you began. Write your letter in complete sentences. Use each of the following terms correctly in your letter: • condensation • evaporation • precipitation • collection (HELP PLS ILL GIVE 54 points *all my points* AND GIVE BRAINLIEST HELP PLS)
Answer:
Explanation:
One day I was sitting on a leaf, in the early morning if a Tuesday, and I was just relaxing there. I then heard Bob( the water molecule next to me) say that he heard it was going to get pretty hot today. As the day went on I started to get pretty warm and I starting to evaporate and fly into the sky! It was really weird to see the world from up high. I stayed up there bouncing between clouds with Bob for a few hours, until the wind started to pick up and it got colder. I then started to shiver and began condensing with the other water molecules (and Bob). As it got colder we began to plummet to the earth really fast in the precipitate form of a water droplet. We hit the ground with a big ker-plop! I looked around me and we weren't the only ones. A bunch of other droplets had started to collect and form a puddle.
Hope this helps!
On the spectrum, which section has the longest wavelength and the shortest wavelength? (2 answers for this question)
Answer:
Radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays are all types of electromagnetic radiation. Radio waves have the longest wavelength, and gamma rays have the shortest wavelength.Hope i help youName two elements that have the same properties as sodium (Na)
Answer: Any Alkali metal
Explanation:
T he cool thing about the periodic table is the way it is organized. You can find chemical with similar properties is just looking in the column they are in in to determine the answer. Since Na is in the first column, any of these answer can work:
Li, K, Rb, Cs, and Fr
1.The two green substances are not same thing because some of their properties are different and some of them are the same. If they were the same substance, all of their properties would have to be the same.
How could the explanation be improved?
Answer:
Even though the two substances possess many similarities, they have some unique properties. In turn, since they have the same properties, if they were the same substance, it would make matters worse, if the same chemical was in two different places, there would not be a difference between them since they are the same, just as it is with are two different chemicals would have differing properties since they are two properties would vary from one another since they are 2 totally different things!
Explanation:
In order for a chemical reaction to take place, a certain amount of _____ must be present.
Answer:
The answer is energy. Please give me Brainliest!
Explanation:
Raising the concentrations of reactants makes the reaction happen at a faster rate. For a chemical reaction to occur, there must be a certain number of molecules with energies equal to or greater than the activation energy.
How do you think dry cleaning works?
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Ca+P criss cross method
Answer:
[tex]t \o \: know \: the \: answer \: [/tex]
[tex]refer \: to \: the \: attatchment[/tex]
Explanation:
Hope this helps !!Please help.
Why does the temperature change when a powder is dissolved in water?
Answer:
In order for the powder to dissolve, each powder molecule must separate from the other powder molecules and be surrounded by water molecules. This shift in arrangement either absorbs or releases energy depending on the situation. It is due to the exchange of energy that the temperature of the solution fluctuates.
Explanation:
:)
Compare sodium and silver before and after they are placed in water. Has a new substance been produced in each case?
Answer:
Sodium is placed in group 1 of the periodic table of Alkali metals, and has a valence shell with one electron, making them very reactive. When placed in water, it disperses heat and begins to ignite and burn (due to its very reactive nature), resulting compound is hydrogen gas (H2), and a very strong base (Sodium Hydroxide, NaOH) used for cleaning appliances and for neutralizing agents.
Silver is placed on the transitional metal section of the periodic table, not quite reactive but is the most conductible element on the planet, is malleable and ductile. Due to it being costly and its rarity, it's not relied on for computer parts or wires. Silver doesn't actually directly react with water in its liquid state. It does produce hydrogen gas and Silver Oxide when reacting with water vapour.
In short, Sodium and water create new products, while Silver and water (only in water's gaseous form) form different products.
