Answers
Answer: The number of series in Mendeleev's Periodic table is 12.
Explanation:
Horizontal rows present in the periodic table are called periods. Vertical rows in the periodic table are called series.
Mendeleev gave periodic table in the year 1869 by arranging elements according to their atomic weights a in tabular form.
Mendeleev's periodic table depicts 12 periods/series.
Thus, we can conclude that the number of periods/series in Mendeleev's Periodic table is 12.
Related Questions
Calculate the volume in liters of a 1.60 mol/L sodium nitrate solution that contains of sodium nitrate . Round your answer to significant digits.
Answers
Answer:
1.5L of NaNO3 must be present
Explanation:
That contains 200g of sodium nitrate. Round to 2 significant digits
To solve this question we need to convert the mass of NaNO3 to moles using its molar mass (85g/mol). With the moles and the molar concentration we can find the volume in liters of the solution:
Moles NaNO3:
200g * (1mol / 85g) = 2.353 moles NaNO3
Volume:
2.353 moles NaNO3 * (1L / 1.60moles) =
1.5L of NaNO3 must be presentDraw a sketch showing what osmotic pressure is. Label on the sketch solute, solvent, hypertonic, hypotonic and semi permeable membrane.
Answers
Voltages listed in textbooks and handbooks are given as standard cell potentials (voltages). What is meant by a standard cell?
Answers
Answer:
Find the definition below.
Explanation:
A standard cell is a group of transistors that have a regular electromotive force flowing through them. They follow either the boolean function or the storage function. A technology library that is made up of a collection of standard cells can be used to facilitate the placement, routing, and synthesis of the Application-specific Integrated Circuit (ASIC).
Electronic Design Automation is an example of an apparatus that implements this functionality.
What is the phase change from solid to gas?
O A. Condensation
O B. Sublimation
O C. Freezing
O D. Vaporization
Answers
Answer:
The answer is B, sublimation.
Answer:
The correct answer
B . Sublimation
How do you predict the geometrical shape of NH3 on VSEPR model
Answers
Answer:
NH3 Ammonia
Explanation:
Ammonia has 4 regions of electron density around the central nitrogen atom (3 bonds and one lone pair). These are arranged in a tetrahedral shape. The resulting molecular shape is trigonal pyramidal with H-N-H angles of 106.7°.
A sealed container was filled with 0.300mol H2(g), 0.400mol I2(g), and 0.200mol HI(g) at 870K and total pressure 1.00bar. Calculate the amounts of the components in the mixture at equilibrium given that K.= 70 for the reaction H2(g)+I2(g) --> 2HI(g).
Answers
Answer:
[HI] = 0.704mol
[H2] = 0.048mol
[I2] = 0.148mol
Explanation:
Based on the equilibrium:
H2(g)+I2(g) --> 2HI(g)
The equilibrium constant, K, is defined as:
K = 70 = [HI]² / [H2] [I2]
Where [] could be taken as the moles in equilibrium of each reactant
To know the direction of the equilibrium we need to find Q with the initial moles of each species:
Q = [0.200mol]² / [0.300mol] [0.400mol]
Q = 0.333
As Q < K, the reaction will shift to the right producing more HI. The equilibrium moles are:
[HI] = 0.200mol + 2X
[H2] = 0.300mol - X
[I2] = 0.400mol - X
Replacing in K:
70 = [0.200 + 2X ]² / [0.300 - X] [0.400 - X]
70 = 0.04 + 0.8 X + 4 X² / 0.12 - 0.7 X + X²
8.4 - 49 X + 70 X² = 0.04 + 0.8 X + 4 X²
8.36 - 49.8X + 66X² = 0
Solving for X:
X = 0.252 moles. Right solution
X = 0.502 moles. False solution. Produce negative moles.
Replacing:
[HI] = 0.200mol + 2*0.252 mol
[H2] = 0.300mol - 0.252 mol
[I2] = 0.400mol - 0.252 mol
[HI] = 0.704mol
[H2] = 0.048mol
[I2] = 0.148mol
A chemistry grad student measures the performance of the new pump in his lab. The result is:Convert to
Answers
Answer:
The correct answer is - 0.0188 mJ*s^-1.
Explanation:
In order to convert the kPA value to PA value--
and then convert PA unit to 1 kgm^-1s^-2
And in finally convert mm to m
The value that come should be convert from kgm^2s^-2 to and then convert J to mJ or kJ by dividing 100 or 100 subsequently.
As no question given this method can be followed for the answer.
Assuming equal concentrations and complete dissociation, rank these aqueous solutions by their freezing points from highest to lowest. CoCl3, NH4Cl, Li2SO4
Answers
Answer:
NH4Cl > Li2SO4 > CoCl3
Explanation:
Let us recall that the freezing point depression depends on the molality of the solution and the number of particles present.
Let us also recall that freezing point depression is a colligative property. It depends on the number of particles present in solution.
Usually, the more the number of particles present, the lower the freezing point. Hence, NH4Cl which has only two particles will have the highest freezing point while CoCl3 which has four particles will have the lowest freezing point.
Water has a density of 1.00 g/mL. If you put an object that has a density of 0.79 g/mL into water, it will sink to the bottom.
ANSWER please
True
False
Answers
Answer:
False
Explanation:
An object with a density less than the density of water will float.
And an object that is denser than water (more than 1.00g/mL) will sink when placed in water.
If you could travel at the speed of light, how long would it take to travel from one side of the Milky Way galaxy to the other?
Answers
Answer:
It would take 200,000 years for a spaceship traveling at the speed of light to go across the entire galaxy.
Amateur radio operators in the United States can transmit on several bands. One of those bands consists of radio waves with a wavelength near 160m. Calculate the frequency of these radio waves on the freauensy of these radio waves.
Answers
Answer:
1.875 × 10^6 Hz
Explanation:
From the wave formula;
V= λf
λ= wavelength of the radio waves
f= frequency of the radio waves
f= v/λ
Since radio waves is an electromagnetic wave, it possesses the speed of light which is 3 × 10^8 m/s
f= 3 × 10^8 m/s/160 m
f= 1.875 × 10^6 Hz
How many grams of h2o are needed to produce 45g of NO
Answers
We need (i) the stoichiometric equation, and (ii) the equivalent mass of dihydrogen.
Explanation:
1
2
N
2
(
g
)
+
3
2
H
2
(
g
)
→
N
H
3
(
g
)
11.27
g
of ammonia represents
11.27
⋅
g
17.03
⋅
g
⋅
m
o
l
−
1
=
?
?
m
o
l
.
Whatever this molar quantity is, it is clear from the stoichiometry of the reaction that 3/2 equiv of dihydrogen gas were required. How much dinitrogen gas was required?
Predict the reactants of this chemical reaction. That is, fill in the left side of the chemical equation. Be sure the equation you submit is balanced. (You can edit both sides of the equation to balance it, if you need to.)
______________ → BaBr2 + H2O
Answers
Answer:
Ba(OH)₂ + 2 HBr ⇒ BaBr₂ + 2 H₂O
Explanation:
We have the products of a reaction and we have to predict the reactants. Since the products are binary salt and water, this must be a neutralization reaction. In neutralizations, acids react with bases. The acid that gives place to Br⁻ is HBr, while the base the gives place to Ba²⁺ is Ba(OH)₂. The balanced chemical equation is:
Ba(OH)₂ + 2 HBr ⇒ BaBr₂ + 2 H₂O
A 46.6-mgmg sample of boron reacts with oxygen to form 150 mgmg of the compound boron oxide. Part A What is the empirical formula of boron oxide
Answers
Answer:
B₂O₃
Explanation:
Step 1: Calculate the mass of oxygen in 150 mg of boron oxide
Of 150 mg of boron oxide, 46.6 mg belong to boron. The mass of oxygen is:
150 mg - 46.6 mg = 103.4 mg
Step 2: Calculate the percent by mass of each element
We will use the following expression.
%Element = mElement/mCompound × 100%
%B = 46.6 mg/150 mg × 100% = 31.1%
%O = 103.4 mg/150 mg × 100% = 68.9%
Step 3: Divide each percentage by the atomic mass of the element
B: 31.1/10.81 = 2.88
O: 68.9/16.00 = 4.31
Step 4: Divide both numbers by the smallest one (2.88)
B: 2.88/2.88 = 1
O: 4.31/2.88 ≈ 1.5
Step 5: Multiply both numbers by 2 so that they are integers
B: 1 × 2 = 2
O: 1.5 × 2 = 3
The empirical formula is B₂O₃.
༒How much does the earth weigh?☆☆☆☆☆☆☆☆☆☆☆☆
Answers
Answer:
Earth has a mass of 5.9736×1024 kg
5.972×10²⁴kghope it is helpful to you
An electron in the ground state absorbs a single photon of light and then relaxes back to the ground state by emitting an infrared photon (1200 nm) followed by an orange photon (600 nm). What is the wavelength of the absorbed photon?
A. 400 nm
B. 600 nm
C. 1800 nm
Answers
Is it better to use graphite or carbon electrodes during electrolysis if I am trying to investigate volume of gas produced ?
Answers
Answer:
yes
Explanation:
it is important for electrolysis
11th grade chemistry question will mark brainliest
2.50 g of CO2 gas is confined in a rigid cylinder at a pressure
of 4.65 atm. If 0.42 g of gas is released from the cylinder,
what is the new pressure?
Answers
Answer:
3.88 atm
Explanation:
We'll begin by calculating the number of mole of CO₂ in each case. This can be obtained as follow:
For 2.50 g of CO₂:
Mass of CO₂ = 2.5 g
Molar mass of CO₂ = 12 + (2×16) = 44 g/mol
Mole of CO₂ =?
Mole = mass / molar mass
Mole of CO₂ = 2.5 / 44
Mole of CO₂ = 0.06 mole
For 0.42 g of CO₂:
Mass of CO₂ = 2.5 g
Molar mass of CO₂ = 44 g/mol
Mole of CO₂ =?
Mole = mass / molar mass
Mole of CO₂ = 0.42 / 44
Mole of CO₂ = 0.010 mole
Finally, we shall determine the new pressure. This can be obtained as follow:
Initial mole (n₁) = 0.06 mole
Initial pressure (P₁) = 4.65 atm
Final mole (n₂) = 0.06 – 0.010 = 0.05 mole
Final pressure (P₂) =?
NOTE: Temperature and volume is constant.
P₁ / n₁ = P₂ / n₂
4.65 / 0.06 = P₂ / 0.05
Cross multiply
0.06 × P₂ = 4.65 × 0.05
0.06 × P₂ = 0.2325
Divide both side by 0.06
P₂ = 0.2325 / 0.06
P₂ = 3.88 atm
Thus, the new pressure is 3.88 atm.
During a reaction, ΔH for reactants is −750 kJ/mol and ΔH for products is 920 kJ/mol. Which statement is correct about the reaction? (5 points)
Group of answer choices
It is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
It is exothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
It is exothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
Answers
Answer: The statement it is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed, is true.
Explanation:
A chemical reaction in which heat energy is released is called an exothermic reaction. For exothermic reactions, the value of [tex]\Delta H[/tex] is always negative.
A chemical reaction in which heat energy is absorbed is called an endothermic reaction. For endothermic reaction, the value of [tex]\Delta H[/tex] is always positive.
In endothermic reactions, energy required for breaking the bonds between reactants is less than the energy when products are formed due to which the value of [tex]\Delta H[/tex] remains positive.
Thus, we can conclude that the statement it is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed, is true.
It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed. The correct option is B.
The above reaction is endothermic because more energy is produced when new bonds form in the products (H = 920 kJ/mol) than is required to break bonds in the reactants (H = -750 kJ/mol).
In an endothermic process, more energy than is generated during bond creation is absorbed from the environment to dissolve existing bonds. This causes a net absorption of energy, which cools the system.
The reaction takes more energy than it releases, proving its endothermic nature, as seen by the positive difference between the energy needed to dissolve bonds and the energy released during bond formation.
Thus, the correct option is B.
For more details regarding endothermic process, visit:
https://brainly.com/question/28909381
#SPJ3
Your question seems incomplete, the probable complete question is:
During a reaction, ΔH for reactants is −750 kJ/mol and ΔH for products is 920 kJ/mol. Which statement is correct about the reaction? (5 points)
Group of answer choices
A. It is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
B. It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
C. It is exothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
D. It is exothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
Which Group is in the second column of the periodic table?
O A. Noble gases
O B. Alkaline earth metals
O C. Alkali metals
O D. Halogens
Answers
Answer:
O B. Alkaline earth metals
Explanation:
Noble gases → 8th column.
Alkali metal → first column.
Halogen → 7th
Answer:
B. Alkaline earth metals
Explanation:
Alkaline-earth metals: The alkaline-earth metals make up Group 2 of the periodic table, from beryllium (Be) through radium (Ra). Each of these elements has two electrons in its outermost energy level, which makes the alkaline earths reactive enough that they're rarely found alone in nature. But they're not as reactive as the alkali metals. Their chemical reactions typically occur more slowly and produce less heat compared to the alkali metals.
Acetic acid and water react to form hydronium cation and acetate anion, like this:
HCH3CO2(aq) + H2O → H3O+(l)(aq) + CH3CO2^-(aq)
Imagine 226 mmol of CH3CO2- are added to a flask containing a mixture of HCH3CO2, H2O, H3O + and CH3CO2- at equilibrium.
Required:
What is the rate of the reverse reaction before any CH3CO2^- has t:een added to the flask?
Answers
Answer:
The rate of the reverse reaction before any addition of CH3CO2- is zero
Explanation:
When the reaction is in equilibrium:
HCH3CO2(aq) + H2O ⇄ H3O+(l)(aq) + CH3CO2^-(aq)
The reaction quotient, Q = Ka and no more products or reactants are produced because their concentrations are in the right proportion.
Now, as no reaction occurs,
The rate of the reverse reaction before any addition of CH3CO2- is zeroA scientist is conducting a Sanger's sequencing experiment to determine the number of polypeptides present in an oligomeric protein. The molecular weight of the protein is 18000 g/mol . After the reaction of 520 mg of the protein with 1‑fluoro‑2,4‑dinitrobenzene, the peptide bonds were hydrolyzed with an acid. As a result, the scientist obtained 39 mg of 2,4‑dinitrophenyl serine. What is the number of the polypeptide chains present in the oligomer?
Answers
Answer:
Depends on molecule.
Explanation:
The number of the polypeptide chains present in the oligomer depends on the molecule. Some molecules have more polypeptide chains whereas some of them have less polypeptide chains. For example, Hemoglobin is a oligomer that consists of four Polypeptide Chains, two of these Polypeptide Chains are α-globin molecules, each comprise of 141 amino acids, and the other two are (β, γ, δ, or ε) globins, each consist of 146 amino acids.
A student dropped a pea size amount of K2CO3 into a solution of HCl(aq). He observed the formation of gas bubbles and collected the gas into another test tube. The student performed a splint test and observed that the splint was extingished when he placed the splint into the test tube of the gas. What can be said about the results of this students experiment?
a. The student completed the experiment correctly and there were no errors in the experiment.
b. The experiment was performed incorrectly. K2CO3 doesn't react with HCl. Therefore, the student picked up the wrong compound when conducting the experiment.
c. The student performed the splint test incorrectly. He should of observed the splint flare up when the splint was placed in the test tube.
d. The student performed the splint test incorrectly. He should of observed a popping sound when the splint was placed in the test tube.
Answers
Answer:
The student completed the experiment correctly and there were no errors in the experiment.
Explanation:
When a pea size amount of K2CO3 is dropped into a solution of HCl, the following reaction occurs;
K2CO3(s) + 2HCl(aq) ----> 2KCl(aq) + CO2(g) + H2O(l)
The gas CO2 does not support burning hence, when the student performed a splint test and observed that the splint was extinguished when he placed the splint into the test tube of the gas.
Hence, the experiment was properly conducted and the student completed the experiment correctly and there were no errors in the experiment.
A balloon contains 0.118 mol of gas and has a volume of 2.58 L . If an additional 0.116 mol of gas is added to the balloon (at the same temperature and pressure), what will its final volume be? Can you also show the work so I can understand why is it that answer. thank you
Answers
Answer:
v2=5.11L
Explanation:
given
v1=2.58L
N1=0.118mol
N2=0.234
v2=x
according to charles law V1/N1=V2/N2
2.58/0.118=V2/0.234
21.86=V2/0.234
21.86×0.234= v2
5.116L=v2
5.116L is the
answer or u can simplify it and make 5.1 L
The first law of thermodynamics defines chemical energy. defines entropy. is a statement of conservation of energy. provides a criterion for the spontaneity of a reaction.
Answers
Answer: The first law of thermodynamics is a statement of conservation of energy.
Explanation:
According to the first law of thermodynamics, heat provided to a system is actually the sum of internal energy and work done by the system or on the system.
Mathematically, [tex]\Delta Q = \Delta U + \Delta W[/tex]
The first law of thermodynamics also means that energy can neither be created nor it can be destroyed. Hence, energy is conserved.
Thus, we can conclude that the first law of thermodynamics is a statement of conservation of energy.
Give the name of the molecular compound and the name of the aqueous solution for each of the binary compounds below.
a. HCN
b. HF
c. H2S
Answers
Explanation:
A compound containing only two elements is called a binary compound.
(a). The compound HCN contains a hydrogen ion and cyanide ion. Hence, the name of HCN is hydrogen cyanide.
An aqueous solution of hydrogen cyanide is known as hydrogen cyanide solution.
(b). The compound HF contains a hydrogen ion and a fluorine ion. The suffix -ide will be added to its name. So, the name of this compound is hydrogen fluoride.
An aqueous solution of HF is known as hydrogen fluoride.
(c). The compound [tex]H_{2}S[/tex] contains two hydrogen atoms and one sulfur atom. The suffix -ide will be added to its name. So, the name of this compound is hydrogen sulfide.
An aqueous solution of this compound is known as hydrogen sulfide solution.
The chemical formula is different from the empirical formula in
Answers
Answer:be careful and relax
Explanation:
Answer:
Hahaha be careful and relax
Observe as equações e de acordo com Brönsted-Lowry, os compostos destacados são, respectivamente
Answers
answer
j'ai besoin d'aide
=]
<3
Identify the intermolecular attractions for dimethyl ether and for ethyl alcohol. Which molecule is expected to be more soluble in water? Explain.
Answers
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.
Which term can be used to describe the process in the reaction below? 2 NaHCO3 (s) → Na2CO3 (s) + H2O (g) + CO2 (g)
Answers
Answer:
Decomposition
Explanation:
If we look at the process;
2 NaHCO3 (s) → Na2CO3 (s) + H2O (g) + CO2 (g)
We can see that NaHCO3 was broken down into Na2CO3, H2O and CO2.
The breakdown of one compound to yield other chemical compounds is known as decomposition.
Hence the NaHCO3 was decomposed in the process above.
