Answer:
.
Elements are arranged from left to right and top to bottom in the order of their increasing atomic numbers. Thus,
Elements in the same group will have the same valence electron configuration and hence, similar chemical properties.
Whereas, elements in the same period will have an increasing order of valence electrons. Therefore, as the energy level of the atom increases, the number of energy sub-levels per energy level increases.
The first 94 elements of the periodic table are naturally occurring, while the rest from 95 to 118 have only been synthesized in laboratories or nuclear reactors.
The modern periodic table, the one we use now, is a new and improved version of certain models put forth by scientists in the 19th and 20th century. Dimitri Mendeleev put forward his periodic table based on the findings of some scientists before him like John Newlands and Antoine-Laurent de Lavoisier. However, Mendeleev is given sole credit for his development of the periodic table.
Determine the percentage of carbon and hydrogen in ethane C2H6 if the molecular weight is 30.
Answer:
Percentage of carbon:
[tex] { \tt{ = \frac{24}{30} \times 100\%}} \\ = 80\%[/tex]
Percentage of hydrogen:
[tex]{ \tt{ = \frac{6}{30} \times 100\%} } \\ = 20\%[/tex]
In the experiment "Preparation and Standardization of a Sodium Hydroxide Solution", why was the burette rinsed with NaOH before filling it to "zero" for the titration?
Answer: The correct option is ALL OF THE ABOVE.
Explanation:
TITRATION is a type of volumetric analysis which is used for determining the concentration of solutions. In this process a specific volume of a solution is placed in a conical flask by means of a pipette and small quantities of a second solution is slowly added from a burette until the end point is reached. This is determined by a means of an indicator which shows a characteristic colour change.
During titration, the following precautions should be followed to avoid errors and maintain standardisation in the experiment.
--> Any air bubble in the burette and pipette must be removed during measurement
--> the burette tap should be tightened to avoid leakage.
--> Remove the funnel from the burette before taking any reading to avoid errors in reading the volume.
--> use the base solution such as Sodium Hydroxide Solution to rinse the burette after washing with soap and tap water:
• to remove any air bubble and fill it's tip
• to remove any residual liquid from the water and soap solution which may interfere with the results of the experiment.
• to check if the burette is in good condition.
Therefore all of the above options to the question are correct.
How much energy is required to melt 2 kg of gold? Use the table below and this equation.
a. 125.6 kJ
b. 1729 kJ
c. 10.4 kJ
d. 3440kJ
The equation for the energy required to melt 2 kg of gold is 3440 kJ.
What is energy?Energy is the ability to do work or cause change. It is an essential part of everyday life and is present in many forms, such as thermal energy, electrical energy, chemical energy, and mechanical energy. Energy can be converted from one form to another in order to do work.
The equation for calculating the energy required to melt a certain mass of material is Q = m x Lf, where Q is the energy required (in joules), m is the mass of the material (in kilograms), and Lf is the latent heat of fusion (in joules per kilogram).
Using the table below, we can see that the latent heat of fusion for gold is 1760 kJ/kg. Therefore, the equation for the energy required to melt 2 kg of gold is: Q = 2 kg x 1760 kJ/kg = 3440 kJ.
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If I have 25g of Sodium, how much Sodium Chloride will I theoretically create?
O 50g NaCl
0 58.3g NaCl
O 63.7g Naci
0 35.4g NaCl
Answer:
64 g
Explanation:
Step 1: Write the balanced equation
2 Na + Cl₂ ⇒ 2 NaCl
Step 2: Calculate the moles corresponding to 25 g of Na
The molar mass of Na is 22.98 g/mol.
25 g × 1 mol/22.98 g = 1.1 mol
Step 3: Calculate the moles of NaCl formed from 1.1 moles of Na
The molar ratio of Na to NaCl is 2:2. The moles of NaCl formed are 2/2 × 1.1 mol = 1.1 mol.
Step 4: Calculate the mass corresponding to 1.1 moles of NaCl
The molar mass of NaCl is 58.44 g/mol.
1.1 mol × 58.44 g/mol = 64 g
Explain what happens when water reacts with sodium metal. Support your answer with the relevant
equation.
Sodium metal reacts rapidly with water to form a solution of sodium hydroxide (NaOH) and hydrogen gas (H2). This reaction is exothermic.
Equation:
2Na + 2H²0 --------}- 2NaOH + H²
A molecule contains hydrogen bonding if it contains hydrogen covalently bonded to Group of answer choices sulfur, oxygen, or fluorine. oxygen or nitrogen. fluorine, oxygen, or nitrogen. nitrogen, fluorine, oxygen, or nitrogen. chlorine, fluorine, or iodine.
Answer: A molecule contains hydrogen bonding if it contains hydrogen covalently bonded to (fluorine, oxygen, or nitrogen)
Explanation:
A hydrogen bond is a strong dipole-dipole attraction which occurs between
--> the hydrogen atom attached to a strongly electronegative atom, and
--> another strongly electronegative atom with a lone pair of electrons.
When an electronegative atom such as fluorine, oxygen or Nitrogen is bonded to hydrogen, a dipole develops causing the hydrogen to be partially negative. The electrostatic attraction between the partially positive hydrogen atom in one molecule and the partially negative atom of the more electronegative element in another molecule gives rise to the strong dipole-dipole attraction called hydrogen bonding.
Hydrogen fluoride, water and ammonia contain the three most electronegative elements, fluorine, oxygen and nitrogen respectively, linked directly to hydrogen. In addition, lone pairs of electrons are present in the fluorine, oxygen and nitrogen atoms of the three hydrides, making hydrogen bonds to form easily between them. These compounds which exhibits hydrogen bonding always have higher melting and boiling points.
There is a type of algae that lives in the cells of corals. These algae process carbon through photosynthesis and pass it on to corals in the form of glucose, a sugar that provides the energy corals need to survive and function. Corals offer protection for the algae and also produce wastes that the algae need for photosynthesis.
Warmer water temperatures caused by global warming disrupt photosynthesis in the algae, causing a poisonous build-up that threatens corals. This causes corals to force the algae out of their cells.
Answer:
Explanation:
Sample Response: If global warming continues, corals will continue to expel the algae from their cells to avoid poisonous buildup. This will cause corals to die. Without corals, the algae are not protected and cannot perform photosynthesis. This will cause the algae to die as well.
Acetoacetyl-ACP is formed as an intermediate during fatty acid biosynthesis. The CO2 used to synthesize malonyl-CoA is lost. Would this help make the reaction more or less energetically favorable
Answer:
This would make the reaction more energetically favourable
Explanation:
Fatty acid synthesis starts with the carboxylation of acetyl CoA to malonyl CoA. This irreversible reaction is the committed step in fatty acid synthesis. The synthesis of malonyl CoA is catalyzed by acetyl CoA carboxylase, which contains a biotin prosthetic group.
A ball is thrown straight up into the air with a speed of 21 m/s. If the ball has a mass of 0.1 kg, how high does the ball go? Acceleration due to gravity is g = 9.8 m/s^2
Answer:
answer = 22.5m
Explanation:
using
[tex]s = \frac{ {v}^{2} - {4}^{2} }{2a} [/tex]
s= (0²-21²)/2(-9.8)
s= -441/19.6
s= 22.5m
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An acid is a substance that produces hydrogen ions in a water solution true or false
Answer:
True I think
hope this helps
Answer:
true
Explanation:
because it reacts with the water molecules by giving a proton to them
Draw the Lewis structure for BrCl3. What are the approximate bond angles about the central atom?
a. 60°.
b. 90°.
c. 109°.
d. 120°.
e. 180°.
Answer:
Explanation:
BrCl₃ is an interhalogen compound with a hybridization of sp³d. The approximate bond angles can be predicted from the structure (attached below). Although, the lewis structure might be predicted to be trigonal bipyramidal from the structure, it is however a T-shaped geometry because of it's two lone pairs.
Also, from the structure attached, it can be predicted that the approximate bond angles about the central atom is 120° (360 ÷ 3) since each of the three chlorine atoms is equally spaced about the central atom.
The Lewis structure for BrCl₃ is attached to the image below. The bond angles around the central atom, bromine (Br), are 90 degrees between the bromine and each chlorine atom. Therefore, option B is correct.
A Lewis structure, also known as an electron-dot structure or Lewis dot structure is a diagram that represents the valence electrons of an atom or molecule.
Bromine (Br) is in Group 7A and has 7 valence electrons, while each chlorine (Cl) atom in Group 7A also has 7 valence electrons.
Br: 1 atom × 7 valence electrons = 7 valence electrons
Cl: 3 atoms × 7 valence electrons = 21 valence electrons
Total valence electrons = 7 + 21 = 28
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If an object has a mass of 243.8 g and occupies a volume of 0.125L, what will be the density of this object in gm/cm3?
Answer:
it might reach to 4g per L
How many doubtful digit(s) is/are allowed in any measured quantity?
(Only 3 choices.)
A.) 1
B.) 2
C.) zero
Answer:
zero
Explanation:
I I think one should be so accurate with measurements and experiments
How many atoms in each elemental sample?
4.9 mol Cu
5.4•10^-3 Mol C
24.0 Mol Hg
0.160 mol Na
Answer:
2.9 × 10²⁴ atoms Cu; 3.3 × 10²¹ atoms C; 1.44 × 10²⁵ atoms Hg; 9.63 × 10²² atoms Na
Explanation:
To convert moles to atoms, we need a conversion factor: Avogadro's number. There are 6.02 × 10²³ atoms in 1 mole of atoms.
4.9 mol Cu × 6.02 × 10²³ atoms Cu/1 mol Cu = 2.9 × 10²⁴ atoms Cu
5.4 × 10⁻³ mol C × 6.02 × 10²³ atoms C/1 mol C = 3.3 × 10²¹ atoms C
24.0 mol Hg × 6.02 × 10²³ atoms Hg/1 mol Hg = 1.44 × 10²⁵ atoms Hg
0.160 mol Na × 6.02 × 10²³ atoms Na/1 mol Na = 9.63 × 10²² atoms Na
this was in my science test just want to see if anyone knows?? the wording is so confusing
the relative atomic mass of an element compares the mass of an atom of an element with the mass of an atom of.......
Answer:
the molar mass of the element
How many molecules of C 2H 5Br will be present if you had 4.52 g of this compound?
Suppose you perform a titration of an unknown weak acid solution. You start with 4.00 mL of the weak acid and find that it takes 14.2 mL of 0.0500 M NaOH to reach the equivalence point. What is the concentration of the unknown weak acid solution
Answer:
0.1775 M
Explanation:
The reaction that takes place is:
HA + NaOH → NaA + H₂OWhere HA is the unknown weak acid.
At the equivalence point all HA moles are converted by NaOH. First we calculate how many NaOH moles reacted, using the given concentration and volume:
0.0500 M NaOH * 14.2 mL = 0.71 mmol NaOHThat means that in 4.00 mL of the weak acid solution, there were 0.71 weak acid mmoles. With that in mind we can now calculate the concentration:
0.71 mmol HA / 4.00 mL = 0.1775 Mwhich is not one of daltons hypothesis of atomic theory
elements are composed of atoms
compounds are composed of atoms of more than one element
a chemical reaction involved the rearranging of atoms
all atoms of a given element are identical
the atoms of one element are the same as another
Answer:
because atoms is just a chemical ahahahah
Explanation:
hope it helps ☺️
Dalton's hypothesis of atomic theory was given by John Dalton. The atoms of one element are the same as another and are not part of Dalton. Thus, option E is correct.
What is Dalton's theory?Dalton gave the atomic theory where atoms are the fundamental unit of the element of the periodic table. More than one element and atoms combine to form molecules and compounds.
The property of the atoms to get rearranged is the basis of the chemical reaction that results in the formation of the new product. This resulted in the formulation of chemical combinations. The atoms of the given element are said to be the same like the potassium contains the same atom.
The atoms of one element cannot be the same as another atom, like the atom of sodium and chloride are not the same. They are different in physical and chemical properties.
These atoms follow the law of conservation of mass. The atoms are composed of sub-atomic particles that have been constituted of neutrons, electrons, and protons.
Therefore, in option E. the atoms of two elements can never be the same.
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If 0.21J of heat cause a 0.308 degree C temperature change, what mass of water is present?
a 0.0702 g
b 0.00540 g
c 0.163 g
d 18.4 g
Answer:
The correct answer is Option c (0.163 g).
Explanation:
Given:
Heat energy,
Q = 0.21 J
Specific heat,
c = 4.184 J/g°c
Change in temperature,
ΔT = 0.308°C
As we know,
⇒ [tex]Q=mc \Delta T[/tex]
By substituting the values, we get
[tex]0.21=m\times 4.184\times 0.308[/tex]
[tex]m=\frac{0.21}{0.308\times 4.184}[/tex]
[tex]=\frac{0.21}{1.28867}[/tex]
[tex]=0.163 \ g[/tex]
Identify the intermolecular attractions for dimethyl ether and for ethyl alcohol. Which molecule is expected to be more soluble in water? Explain.
Answer:
See explanation
Explanation:
All molecules possess the London dispersion forces. However London dispersion forces is the only kind of intermolecular interaction that exists in nonpolar substances.
So, the only kind of intermolecular interaction that exists in dimethyl ether is London dispersion forces.
As for ethyl alcohol, the molecule is polar due to the presence of polar O-H bond. In addition to London dispersion forces, dipole-dipole interactions and specifically hydrogen bonding also occurs between the molecules.
Because ethyl alcohol is polar, it is more soluble in water than dimethyl ether.
What are the concentrations of hydronium and hydroxide ions in a solution with pH 2.6?
Please help omg. Ive been stuck for 15 minutes
Answer:
The concentrations of hydronium and hydroxide ions in a solution with pH 2.6 are 2.51*10⁻³ and 3.98*10⁻¹² respectively.
Explanation:
pH is a measure of the acidity or alkalinity of an aqueous solution. The pH indicates the concentration of hydrogen ions present in certain solutions. Mathematically it is defined as the opposite of the base 10 logarithm or the negative logarithm of the activity of hydrogen ions, whose equation is
pH= -log [H⁺]
So, being pH= 2.6 and replacing in the definition of pH:
2.6= -log [H⁺]
[tex][H^{+} ]=10^{-2.6}[/tex]
[H⁺]=2.51*10⁻³
pOH is a measure of the concentration of hydroxide ions (OH⁻). The sum between the pOH and the pH results in 14:
pOH + pH= 14
So, being pH= 2.6:
pOH + 2.6= 14
pOH= 14 - 2.6
pOH= 11.4
The pOH is defined as the negative logarithm of the activity of the hydroxide ions. That is, the concentration of OH⁻ ions:
pOH= - log [OH⁻]
Being pOH= 11.4 and replacing
11.4= -log [OH⁻]
[tex][OH^{-} ]=10^{-11.4}[/tex]
[OH⁻]= 3.98*10⁻¹²
The concentrations of hydronium and hydroxide ions in a solution with pH 2.6 are 2.51*10⁻³ and 3.98*10⁻¹² respectively.
What quantity of heat is transferred when a 150.0g block of iron metal is heated from 25.0°C to 73.3°C? What is the direction of the heat flow?
The direction of heat flow is increased which means blocks temperature is higher and hotter than it was before
Given the following list of densities, which materials would float in a molten vat of lead provided that they do not themselves melt? Densities (g/mL): lead = 11.4, glass = 2.6, gold = 19.3, charcoal = 0.57, platinum = 21.4.
a. gold and platinum
b. glass and charcoal
c. gold, platinum, glass and coal
d. gold and charcoal
e. None of these
Answer:
b. glass and charcoal
Explanation:
Step 1: Given data
Density of Pb: 11.4 g/mLDensity of Glass: 2.6 g/mLDensity of Au: 19.3 g/mLDensity of charcoal: 0.57 g/mLDensity of platinum: 21.4 g/mLStep 2: Determine which material will float in molten lead
Density is an intrinsic property of matter. Less dense materials float in more dense materials. The materials whose density is lower than that of lead and will therefore float on it are glass and charcoal.
when a polar bond is formed between 2 atoms which atom receives a partial positive charge
Answer:
The less electronegative atom
Explanation:
Water contains polar bonds. Water is made up of oxygen and hydrogen. Oxygen is more electronegative then hydrogen so it is partial negative (because electron spend more time around oxygen in the polar bond), whereas, hydrogen has a partial positive charge as it is less electronegative (electrons spend less time around hydrogen in this polar bond).
Q2.Which is true about potassium?
Extremely unreactive
Not very reactive
Slightly reactive
Very reactive
A chemist measures the amount of oxygen gas produced during an experiment. She finds that 276. g of oxygen gas is produced. Calculate the number of moles of oxygen gas produced.
Round your answer to 3 significant digits.
0.152 moles
Given that:The mass of the oxygen gas produced = 4.87 g
Also, The molar mass of oxygen gas, = = 32 g/mol
The formula for the calculation of moles is shown below:
moles = [tex]\frac{Mass-taken}{Molar-mass}[/tex] *
Thus,
moles = [tex]\frac{4.87g}{32g/mol }[/tex]
Both given values and the answer is in 3 significant digits.
brainlist pls?
*i put a dash between mass and taken as formulas do no spaces
The equilibrium constant (K p) for the interconversion of PCl 5 and PCl 3 is 0.0121:
PCl5 (g) → PCl3 (g) + Cl2 (g)
A vessel is charged with PCl 5 giving an initial pressure of 0.123 atm and yields PCl 3 and Cl 2. At equilibrium, the partial pressure of PCl 3 is ________ atm.
A) 0.0782.
B) 0.0455.
C) 0.0908.
D) 0.0330.
E) 0.123.
Answer: At equilibrium, the partial pressure of [tex]PCl_{3}[/tex] is 0.0330 atm.
Explanation:
The partial pressure of [tex]PCl_{3}[/tex] is equal to the partial pressure of [tex]Cl_{2}[/tex]. Hence, let us assume that x quantity of [tex]PCl_{5}[/tex] is decomposed and gives x quantity of [tex]PCl_{3}[/tex] and x quantity of [tex]Cl_{2}[/tex].
Therefore, at equilibrium the species along with their partial pressures are as follows.
[tex]PCl_{5}(g) \rightarrow PCl_{3}(g) + Cl_{2}(g)\\[/tex]
At equilibrium: 0.123-x x x
Now, expression for [tex]K_{p}[/tex] of this reaction is as follows.
[tex]K_{p} = \frac{[PCl_{3}][Cl_{2}]}{[PCl_{5}]}\\0.0121 = \frac{x \times x}{(0.123 - x)}\\x = 0.0330[/tex]
Thus, we can conclude that at equilibrium, the partial pressure of [tex]PCl_{3}[/tex] is 0.0330 atm.
A solution of the ionic salt NaF
would have _____
pH.
A. An acidic
B. A basic
C. A neutral
Answer:
The answer is basic
Explanation:
Choose letter b or basic. You welcome.
The strong acid and strong base has high rate constant of dissociation. The rate constant for weak acid and base for the dissociation is low, they do not easily dissociate in water. Therefore option B is the correct option.
What are acid and base?Acid is a solution which releases H⁺ hydrogen ion when dissolved in water. Base releases hydroxide ion OH⁻ ion when dissolved in water.
pH is a measurement of amount of hydronium ion H₃O⁺ in a given sample. Strength of acidic nature is directly proportional to the concentration of hydronium ion.
On subtracting pH from 14, we get pOH which measures the concentration of hydroxide ion in a given solution. Temperature affect the pH. At room temperature pH scale is between 0 to 14. 7 is the pH of neutral solution. A solution of the ionic salt NaF is basic in nature.
Therefore, option B is the correct option.
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Nickel + oxygen = nickel oxide. What is the balanced redox reaction?
Answer:
This is an oxidation-reduction (redox) reaction:
2 Ni0 - 4 e- → 2 NiII
(oxidation)
2 O0 + 4 e- → 2 O-II
(reduction)
Ni is a reducing agent, O2 is an oxidizing agent.
Wine goes bad soon after opening because the ethanol dissolved in it reacts with oxygen gas to form water and aqueous acetic acid , the main ingredient in vinegar. Calculate the moles of acetic acid produced by the reaction of of ethanol. Be sure your answer has a unit symbol, if necessary, and round it to significant digits.
Answer:
The answer is "It takes 1,70 mol of ethanol".
Explanation:
To make acetic acid, we must first write the balanced reaction that occurs of ethanol with oxygen
The response is balanced:
[tex]CH_3CH_2OH+O_2\to CH_3COOH+H_2O[/tex]
1 mol of ethanol creates 1 mol of According the equilibrium Ethanol moles, therefore, required 1.70 mol of water = 1.70 mol
