Answer:
Explanation:
Polyatomic ions are ions (usually anions) that are made up of more than one atom. In order to determine the charge of anions, one can first identify the charge of the metal (which forms the cation) in a compound (which is usually easy to know) before predicting the charge of the anion. The charges are usually exchanged to form denominator of the other reacting atom/molecule, but if divisible, they are divided first before the exchange.
(a) The polyatomic ion in KNO₂ is NO₂ with the ionic equation below showing it's charge
KNO₂ ⇒ K⁺ + NO₂⁻
From the above, we can deduce that the charge of NO₂ is "1-"
(b) The polyatomic ion in CaSO₄ is SO₄ with the ionic equation below showing it's charge
CaSO₄ ⇒ Ca²⁺ + SO₄²⁻
The charge of SO₄ from the above equation is "2-"
(c) The polyatomic ion in Mg(NO₃)₂ is NO₃ with the ionic equation below showing it's charge
Mg(NO₃)₂ ⇒ Mg²⁺ + NO₃⁻
From the above equation, it can be deduced that the charge of NO₃ is "1-"
Helium is more reactive than magnesium.
TRUE
FALSE
Answer: FALSE
Explanation: Magnesium is more reactive.
Hope this helps!
Answer:
False
Explanation:
Magnesium is more reactive.
How many m^3 are in 56cm^3?
Answer:
5.6 × 10-5 m^3
Explanation:
Hope this helps
A jet airplane flies from St. Louis, Missouri, to Phoenix, Arizona, in 3 hrs. The distance is
1,500 miles. What is the plane's speed ?
Answer:
Distance = 1500miles
time taken = 3 hours
speed of plane = distance/time taken = 1500/3= 500milesperhour
Explanation:
According to the distance formula , the speed of the plane is 500 miles per hour.
What is speed?The speed of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit interval of time indicating that it is thus a scalar quantity.The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero. Speed is not the same as velocity.
Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or in the US and the UK, miles per hour (mph).
Here, speed is calculated as distance /time= 1500/3= 500 miles per hour.
Thus, the speed of plane is 500 miles per hour.
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19) What did Rutherford's experiment show?
Answer:
experiment showed that the atom is mostly empty space with a tiny, dense, positively-charged nucleus.
Explanation:srry im late but i dont be on it like that hoped it helped tho srry
Which of the following represents the least number of molecules?
(a) 20.0 g of H2O (18.02 g/mol)
(b) 77.0 g of CH4 (16.06 g/mol)
(c) 68.0 g of CaH2 (42.09 g/mol)
(d) 100.0 g of N2O (44.02 g/mol)
(e) 84.0 g of HF (20.01 g/mol)
Answer:
A ; 20g of water has the least number of molecules
Explanation:
Here, we want to know which of the options represent the least number of molecules;
To calculate this, we are going to first calculate the number of moles using the formula below;
Number of moles = mass/molar mass
Then from the number of moles, we can calculate the number of molecules by multiplying the number of moles by 6.02 * 10^23 molecules
Let’s proceed;
a. That will be 20/18.02 = 1.1099 moles
1.1099 * 6.02 * 10^23 = 6.68 * 10^23 molecules
b. That will be 77/16.06 = 4.8 moles
4.8 * 6.02 * 10^23 = 2.89 * 10*24 molecules
c. That will be 68/42.09 = 1.62 moles
1.62 * 6.02 * 10^23 = 9.73 * 10^23 molecules
d. That will be 100/44.02 = 2.27 moles
2.27 * 6.02 * 10^23 = 1.37 * 10^24 molecules
e. That will be = 84/20.01 = 4.2 moles
4.2 * 6.02 * 10^23 = 2.53 * 10^24 molecules
From all the values obtained, the lowest is 20g of water
I need helpp!!!!!!!!!
A diprotic acid, H₂A, has Ka1 = 3.4 × 10⁻⁴ and Ka2 = 6.7 × 10⁻⁹. What is the pH of a 0.18 M solution of H₂A?
Answer:
pH = 2.10
Explanation:
We name an acid as diprotic because it can release two protons:
H₂A + H₂O ⇄ H₃O⁺ + HA⁻ Ka₁
HA⁻ + H₂O ⇄ H₃O⁺ + A⁻² Ka₂
We propose the mass balance:
Analytical concentration = [H₂A] + [HA⁻] + [A⁻²]
As Ka₂ is so small, we avoid the [A⁻²] so:
0.18 M = [H₂A] + [HA⁻]
But we can not avoid the HA⁻, because the Ka₁. Ka₁'s expression is:
Ka₁ = [H₃O⁺] . [HA⁻] / [H₂A]
We propose the charge balance:
[H₃O⁺] = [HA⁻] + [A⁻²] + [OH⁻]
As we did not consider the A⁻², we can miss the term and if
Kw = H⁺ . OH⁻
We replace Kw/H⁺ = OH⁻. So the new equation is:
[H₃O⁺] = [HA⁻] + Kw / [H₃O⁺]
The acid is so concentrated, so we can avoid the term with the Kw, so:
[H₃O⁺] = [HA⁻]
In the mass balance we would have:
0.18 M = [H₂A]
We replace at Ka₁
Ka₁ = [H₃O⁺] . [HA⁻] / [H₂A]
Ka1 . 0.18 / [H₃O⁺] = [HA⁻]
We replace at the charge balance:
[H₃O⁺] = Ka1 . 0.18 / [H₃O⁺]
[H₃O⁺]² = 3.4×10⁻⁴ . 0.18
[H₃O⁺] = √(3.4×10⁻⁴ . 0.18)
[H₃O⁺] = 7.82×10⁻³
- log [H₃O⁺] = pH → - log 7.82×10⁻³
pH = 2.10
Following are the calculation to the pH:
For First ionization:
[tex][H^+] = (K_{a1} \times C)^{\frac{1}{2}}[/tex]
where
C = initial concentration of acid [tex]= 0.18\ M[/tex]
[tex][H^{+}] = (3.4 \times 10^{-4} \times 0.18 \ M)^{\frac{1}{2}}\\[/tex]
[tex][H^{+}] = 0.007\ M[/tex]
For Second ionization:
[tex][H^{+}] = K_{a2} \\\\[/tex]
[tex][ H^{+} ] = 6.7 \times 10^{-9}\ M \\[/tex]
[tex]Total [H^{+}] = 0.007\ M + 6.7 \times 10^{-9}\ M\\\\Total [H^{+}] = 0.007 \ M[/tex]
[tex]pH = -\log[H^+] \\\\pH = -\log(0.007 \ M)\\\\pH = 2.15[/tex]
Therefore, the pH is "2.15".
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Explanation:
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why do NH3 and SO3 have different bond angles, even though they have the same number of atoms?
Answer:
Due to different atoms and different values of electronegativities.
Explanation:
NH3 and SO3 have different bond angles because both molecules have different type of atoms combine together. In NH3, nitrogen react with hydrogen while in SO3, sulfur react with oxygen atom. The bond angle of NH3 is 107 while the bond angle of SO3 is 120. This difference in bond angle is also due to different electronegativities of the bonded atoms. The electronegativity of oxygen is higher than hydrogen so repulsion of hydrogen is less and that's why its bond angle is also lower than oxygen.
an element has atomic number and mass number 13 and 27 respectively. what are the number of electrons protons and neutrons in one atom of the element
Answer:
the number of electrons is 13 and neutrons is 14
An element has a mass number of 9 and 5 neutrons. What element is it?
Answer:
Fluorine
Fluorine is the element in question, as its atomic number is 9 . You would name this particular isotope using the mass number. It would be called fluorine-19.
Explanation:
Answer:
Fluorine
Fluorine is the element in question, as its atomic number is 9 . You would name this particular isotope using the mass number. It would be called fluorine-19.
Which of the following statements about 13C NMR is not true?A. In 13C proton-decoupled NMR spectra, all peaks are singlets.B. 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.C. 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry
Answer: .B. 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.
Explanation:
The statements that are true about 13C NMR are:
A. In 13C proton-decoupled NMR spectra, all peaks are singlets.
C 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.
D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry
Therefore, the option that isn't true is option B. "13C NMR spectra display peaks for only carbons that bear hydrogen atoms". This is false because 13C NMR will show every peak in the spectrum and it doesn't matter if it's only carbons that bear hydrogen atoms as everything will be shown.
Which of the following is a homogenous mixture? a. water b. chicken c. raisin bread d. salad
B and C are ur answers
1) Use the Born-Haber cycle and given data ΔH∘fKCl = -436.5 kJ/mol, IE1(K) = 419 kJ/mol, ΔHsub(K)=89.0 kJ/mol, Cl2(g)bondenergy = 243 kJ/mol, EA(Cl) = -349 kJ/mol to calculate the lattice energy of KCl.
2) Use the Born-Haber cycle and data from Appendix IIB and Table 9.3 in the textbook to calculate the lattice energy of CaO. You may need the following data: electron affinity of oxygen EA1=−141kJ/mol, EA2=744kJ/mol; ionization energy of calcium IE1=590kJ/mol, IE2=1145kJ/mol, the enthalpy of sublimation for calcium ΔHsub=178kJ/mol.
Answer:
Explanation:
1 ) Let the lattice energy per mole be x
2 K + Cl₂ = 2KCl
Applying Born- Haber cycle
2 x 89 + 2 x 419 + 243 - 2 x 349 + Δx = - 2 x 436.5
178 + 838+ 243 - 698 + Δx = - 873
Δx = 1434 kJ
Lattice energy per mole = 1434 / 2 = 717 kJ / mol
2 )
2Ca + O₂ = 2 CaO
Heat of formation of CaO = - 635 kJ
Let lattice energy be x / mol
Bond energy of oxygen = 498 kJ / mol
178 x 2 + 2 ( 590 + 1145 ) + 498 + 2 ( 744 - 141 ) + x = - 2 x 635
356 + 3470 + 1206 + 498 + 2 x = - 1270
5530 + 2 x = - 1270
x = - 3400 kJ
The lattice energy for each specie can be calculated form the Born - Haber cycle and Hess law.
a) Given that;
Heat of formation (ΔH∘f) = -436.5 kJ/mol
Ionization energy (IE) = 419 kJ/mol
Heat of sublimation(ΔHsub) = 89.0 kJ/mol
Bond energy (BE) = 243 kJ/mol
Electron affinity (EA) = -349 kJ/mol
Lattice energy (U) = ?
From Hess law;
ΔH∘f = ΔHsub + BE + IE + EA + U
U = ΔH∘f - [ΔHsub + BE + IE + EA]
U = ( -436.5 kJ/mol) - [89.0 kJ/mol + 243 kJ/mol + 419 kJ/mol + ( -349 kJ/mol)]
U = -838.5 kJ/mol
b)
Heat of formation (ΔH∘f) =-635 kJ/mol
Ionization energy (IE) =IE1 + IE2 = 1735 kJ/mol
Heat of sublimation(ΔHsub) = 178kJ/mol
Bond energy (BE) = 498 kJ/mol
Electron affinity (EA) = EA1 + EA2 = 603 kJ/mol
Lattice energy (U) = ?
From Hess law;
ΔH∘f = ΔHsub + BE + IE + EA + U
U = ΔH∘f - [ΔHsub + BE + IE + EA]
U = (-635 kJ/mol) - [ 178kJ/mol + 498 kJ/mol + 1735 kJ/mol + 603 kJ/mol]
U = -3649 kJ/mol
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Mendeleev's periodic table was organized by
mendeleev arranged the elements in order of increasing relative atomic mass. When he did this he noted that the chemical properties of the elements and their compounds showed a periodic trend
Answer:
Left to right
Elements are arranged by increasing atomic mass
Naturally occurring boron has an atomic mass of 10.810 amu consists of two isotopes. One of those isotopes is 10B with an isotopic mass of 10.0129 amu and an abundance of 19.9%. What is the isotopic mass of the other isotope?
Answer:
boron has an atomic mass of 10.810 amu consists of two isotopes.
Answer:
boron has an atomic mass of 10.810 amu consists of two isotopes.
Explanation:
I am timed please help!!
Answer:
it is a mixture
element are pure and compound are formed in a fixed ratio
Explanation:
The graph below shows the speed of a downhill
skier during a period of several seconds. Use the
graph to answer Question 13.
16
12
Speed (m/s)
8
0
1
3
3
2
Time (s)
13. Read Graphs What is the skier's acceleration?
Answer:
16
Explanation:
What happens to the principle energy level number when moving from s to p sub levels
Answer:
The principal energy level remains the same
Explanation:
A principal energy level is one defines where electrons reside in an atom and that can contain one or more sub levels and have 2·n² number of electrons located in different sub levels within the energy level. Therefore, when moving up from s to p within the same principal energy level, the principal energy level does not change value.
Some studies have found that when a person mimics an angry expression, their temperature actually rises.
O A True
OB.
False

How does the arrangement of atoms differ in crystals and glass?
How does the arrangement of atoms differ in a crystalline and a noncrystalline substance? Crystals have well organized arrangement of atoms. Non crystals have irregular unorganized arrangement of atoms. You just studied 13 terms!
Who were the terrorists that attacked the united states on September 11, 2001
Science is based primarily on peoples opinions and views of the subject matter.
True or false
Answer:
False
Explanation:
Science is not based on primarily on peoples opinions and views of the subject matter whereas science is based on empirical observations and research for its validity.
Science aims to find answers to human questions related to the natural world through their research observation and experiments. Scientists and researchers provide valid proof of human questions so that people can trust them.
Science can change people's opinions regarding the natural world with valid proof and observational theories but science is not based on people's opinion.
Hence, the given statement is "false".
Chlorine could combine with _ to gain the extra electron it needs to stabilize its outer shell
outer shell.
A. helium
B. sulfur
C. hydrogen
D. none of these
Answer:
C, hydrogen.
Explanation:
I have a buddy who recycles electronics, and isolates metals from the connector pins electrical boards. He isolates gold, for example, and purifies it the best he can, then sells it along with his other scrap metal. This last go around he was able to isolate 3.00 g of Au with a process he claims results in a 80.0% yield. If he is correct, what was his theoretical yield
Answer:
Theoretical yield = 3.75g
Explanation:
Percent yield is defined as one hundred times the ratio between actual yield and theoretical yield. The expression is:
Percent yield = Actual Yield / Theoretical Yield * 100
In the problem, your actual yield was 3-00g.
Percent yield is 80.0%.
Solving for theoretical yield:
80% = 3.00g / Theoretical yield * 100
Theoretical yield = 3.00g / 80.0% * 100
Theoretical yield = 3.75gAtoms of the same element can have different forms; for example, carbon-12 and carbon-14.
What causes the different forms?
What are these forms called?
1)
Which of the following would a chemist be most likely to study?
A what happens when a moving car comes to a stop
B.
what happens when iron rusts in the presence of water
C. what happens when ice melts to form liquid water
D. what happens when light reflects from a shiny surface
Answer:
B. what happens when iron rusts in the presence of water
Explanation:
Chemistry is a branch of science involving the composition and changes of matter. In other words, a chemist, who is a trained specialist in the science of chemistry, seeks to answer questions related to properties of matter.
In this question, a chemist is most likely to study "what happens when iron rusts in the presence of water" because it involves a change in the chemical properties of a substance (iron) i.e. a chemical change. However, what happens when ice melts to liquid water is a physical change.
1) Chemistry is a (physical/biological) science?
Answer:
Explanation:
Biological.
I hope I helped you! :)
Which of the following gases is the least soluble in water and why? CO2, SO3, N2, NH3, HCl.
Answer:
SO3
It has the highest molar mass value and thus would be the least soluble
Explanation:
In this question, we want to know which of the gases is the least soluble in water.
The easiest way to do this is to calculate the molar masses of these gases. The gas with the highest molar mass is the heaviest and thus will be the least soluble in water
For CO2 - molar mass is 44 g/mol
For SO3- molar mass is 80 g/mol
For N2- molar mass is 28g/mol
For NH3-molar mass is 17g/mol
For HCl- molar mass is 36.5 g/mol
From the molar masses, we can see that the molar mass of the ammonia gas is the lightest and thus, it is the most soluble.
The mass of the sulphur vi oxide is the highest and thus it is the heaviest and the least soluble in water
A scuba tank has pressure of 195 kpa at temperature 10 c the volume of the tank is 350 L how many grams of air ins in the tank?
Answer:
[tex]m=840.88g[/tex]
Explanation:
Hello,
In this case, considering the ideal gas equation as:
[tex]PV=nRT[/tex]
We can first compute the moles of air at the given conditions of 195 kPa (1.92 atm), 10 °C (283K) and 350 L:
[tex]n=\frac{PV}{RT}=\frac{1.92atm*350L}{0.082\frac{atm*L}{mol*K}*283K}\\ \\n=29.03molAir[/tex]
Next, since the molar mass of air is 28.97 g/mol, the mass is computed to be:
[tex]m=29.03mol*\frac{28.97g}{1mol} \\\\m=840.88g[/tex]
Best regards.