Answer:
Reactants
Explanation:
Please please help!
What is the mass percent of potassium chloride when 9.35 grams of potassium chloride is mixed into 162.98 grams of water? Choose the answer with the appropriate significant figures and choose the correct unit.
The mass percent of potassium chloride is 1.386%
calculation
mass percent = actual mass/ Theoretical mass x 100
Actual mass = 9.35 g
Theoretical mass is calculated as below
Step 1 : write the equation for reaction
KCl + H₂O → KOH + HCl
Step 2: find the moles of H₂O
moles = mass÷ molar mass
The molar mass of H₂O = (2 x1 ) +(16) = 18 g/mol
moles is therefore = 162.98 g÷ 18 g/mol =9.054 moles
Step 3: use the mole ratio to determine the moles of KCl
KCl: H₂O is 1:1 therefore the moles of KCl is also = 9.054 moles
Step 4: find the theoretical mass of KCl
mass = moles x molar mass
from periodic table the molar mass of KCl = 39 +35.5 =74.5 g/mol
mass = 9.054 moles x 74.5 g/mol =674.5 g
Theoretical mass is therefore = 9.35 g/ 674.5 g x 100 = 1.386%
Write the ionic charges (such as Ca2+) and chemical formulas and fill-in the table below.
Element Names Ionic charges Chemical formula
Lithium and fluorine:
Beryllium and oxygen:
Magnesium and fluorine:
Aluminum and chlorine:
Beryllium and nitrogen:
1) Lithium and fluorine:
Ionic charges: lithium cation Li⁺ and fluorine anion F⁻.
Chemical formula LiF.
In ionic salt lithium fluoride (LiF), fluorine has electronegativity approximately χ = 4 and lithium χ = 1 (Δχ = 4 - 1; Δχ = 3).
Fluorine attracts electron and it has negative charge and lithium has positive charge.
2) Beryllium and oxygen:
Ionic charges cation Be²⁺ and anion O²⁻.
Chemical formula is BeO.
Beryllium is metal from group 2 and oxygen is nonmetal from group 16.
Electron configuration of beryllium: ₄Be: 1s² 2s², it has two valence electrons in 2s orbital.
Beryllium lose two electrons and to gain electron configuration as noble gas helium (He).
Electron configuration of oxygen atom: ₈O 1s² 2s² 2p⁴.
Oxygen gain two valence electron to form anion with stable electron configuration as noble gas neon (atomic number 10).
3) Magnesium and fluorine:
Ionic charges cation Mg²⁺ and anion F⁻.
Chemical formula is MgF₂.
Magnesium fluoride (MgF₂) is salt, ionic compound.
Magnesium (Mg) is metal from 2. group of Periodic table of elements and has low ionisation energy and electronegativity, which means it easily lose valence electons (two valence electrons).
Magnesium has atomic number 12, which means it has 12 protons and 12 electrons. It lost two electrons to form magnesium cation (Mg²⁺) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.
Fluorine (F) is nonmetal with greatest electronegativity, which means it easily gain electrons.
Fluorine has atomic number 9, which means it has 9 protons and 9 electrons. It gain one electron to form fluorine anion (F⁻) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.
4) Aluminum and chlorine:
Ionic charges cation Al³⁺ and anion Cl⁻.
Chemical formula is AlCl₃.
The right name for AlCl₃ is aluminium chloride.
Aluminium chloride is a salt with ionic bonds.
Aluminium (metal from group 13) has oxidation number +3 and chlorine (nonmetal from group 17) has oxidation number -1, chemical compound has neutral charge (+3 + 3 · (-1) = 0).
5) Beryllium and nitrogen:
Ionic charges cation Be²⁺ and anion N³⁻.
Chemical formula is Be₃N₂.
Atomic number of nitrogen is 7, it has 7 protons and 7 electrons.
Electron configuration of nitrogen atom: ₇N 1s² 2s² 2p³.
Nitrogen gain three electrons to form anion with stable electron configuration as noble gas neon (atomic number 10).
The ionic charges and chemical formulas are Li⁺ and F⁻ making lithium fluoride,Be²⁺and O²⁻giving BeO,Mg²⁺ and F⁻ forming MgF₂,Al³⁺and Cl⁻ forming AlCl₃,Be²⁺and N³⁻ forming Be₃N₂.
In LiF ,lithium is Li⁺ and fluorine is F⁻,giving chemical formula LiF.
In BeO beryllium is Be²⁺ and oxygen is O²⁻making chemical formula BeO. In MgF₂ magnesium is Mg²⁺and fluorine is F⁻giving chemical formula MgF₂ .
In AlCl₃ aluminium is Al³⁺while chlorine is Cl⁻ thus AlCl₃ is formed.In Be₃N₂,beryllium is Be²⁺and nitrogen is N³⁻ thus chemical formula is Be₃N₂.
Thus, the name of chemical formula along with ionic charges is given in the attached image.
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What is the simplest formula of a solid containing a, b, and c atoms in a cubic lattice in which the a atoms occupy the corners, the b atoms the body-center position, and the c atoms the faces of the unit cell?
a. a4bc3
b. abc6
c. abc3
d. abc
e. a8bc6?
Answer:
c. abc₃
Step-by-step explanation:
1. a atoms
There are eight corners, each containing an a atom.
No. of a atoms = 8 × ⅛
No. of a atoms = 1
=====
2. b atoms
There is one central b atom.
=====
3. c atoms
There are six faces, each containing a c atom.
No. of a atoms = 6 × ½
No. of c atoms = 3
=====
4. Formula
The simplest formula is abc₃.
The simplest formula of a solid containing a, b, and c atoms in a cubic lattice is: c. [tex]abc_3[/tex]
A unit cell can be defined as a repetitive unit of solid structures with equivalent edge points and opposite faces.
In crystal lattices, there are three (3) main types of unit cell and these include:
Body-centered cubic (BCC)Face-centered cubic (FCC)Simple cubicA simple cubic unit cell is the simplest repetitive unit cell because the lattice points are only at the corners.
To calculate the simplest formula of a solid containing a, b, and c atoms in a cubic lattice:
For a atoms:
[tex]a = 8 \times \frac{1}{8}[/tex]
a = 1 atom
For b atoms:
[tex]b = 1 \times 1[/tex]
b = 1 atom
For c atoms:
[tex]c = 6 \times \frac{1}{2}[/tex]
c = 3 atoms
Simplest formula = [tex]abc_3[/tex]
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Copper has been used in electrical wiring for two hundred years. Identify which molecular level property does not contribute to copper's usefulness a material for wiring.
A) high ductility
B) high malleability
C) high conductivity
D) high crystallinity
Answer:D
Explanation:
Copper is considered as a transition metal on the periodic table. It is highly malleable, shiny and soft. It is often mixed with other metals like tin and zinc to make brass and bronze for electrical wiring. The high crystallinity does not contribute to wiring. The correct option is D.
What is crystallinity?The term crystallinity refers to the degree of structural order and regularity in the molecular arrangements of a material. The degree of crystallinity has a significant influence on material properties like hardness, density, melting point and diffusion.
Copper is a crystalline solid. The solids which have a sharp melting point and definite heat of fusion are called crystalline solids. Electron mobility is the reason why most metals conduct electricity. The electrons can move freely within the metal.
So ductility and conductivity of copper is responsible for it to use in wiring.
Thus the correct option is D.
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Scientists have developed a new drug known to cure a previously incurable disease. What best explains if the new drug is a compound or not?
A) It is a compound because it will be able to cure a disease
B) It is not a compound because it was developed by scientists.
C) It is a compound because compounds make all types of matter.
D) It is not a compound because compounds make up only living things.
Answer should be C, compounds make up all types of matter.
Scientists have developed a new drug known to cure a previously incurable disease. The best explanation if the new drug is a compound or not is that it is a compound because compounds make all types of matter. Hence, option C is correct.
The fact that the new drug is known to cure a previously incurable disease does not determine whether it is a compound or not. The term "compound" refers to a specific type of chemical substance made up of two or more elements that are chemically bonded together. Compounds can be found in various forms and can have different applications, including pharmaceutical drugs like the one mentioned.
The development of the drug by scientists (option B) or its ability to cure a disease (option A) does not provide any information about whether it is a compound or not. Similarly, option D is incorrect because compounds can be found in both living and non-living things, depending on the chemical composition and bonding of the elements involved.
Ultimately, the classification of the new drug as a compound would depend on its chemical composition and whether it consists of multiple elements chemically bonded together.
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In a mixture of argon and hydrogen, occupying a volume of 1.18 l at 894.6 mmhg and 44.1oc, it is found that the total mass of the sample is 1.25 g. what is the partial pressure of argon?
To solve the question, there is a need to use the equation:
PV = nRT
(894.6/760) × 1.18 = n × 0.0821 × (273 + 44.1)
By solving we get:
Total moles, n = 0.053
Assume, the moles of argon as a and of hydrogen as b,
So,
40 × a + 2 × b = 1.25 --------- (i)
a + b = 0.053 ------- (ii)
By solving i and ii we get:
a = 0.03,
Thus, mole fraction of Ar = XAr = 0.03/0.053 = 0.57
So,
Partial pressure of Ar = 894.6 × XAr = 894.6 × 0.57 = 509.92 mm Hg
To find the partial pressure of argon in a mixture of argon and hydrogen, you must utilize Dalton's law, the ideal gas law, and molar masses of argon and hydrogen. Convert the given volume of the mixture into moles, find the total mass, and determine the fraction of argon in the mixture. This fraction, multiplied by the total pressure will give the partial pressure of argon.
Explanation:The calculation of the partial pressure of argon in a mixture of argon and hydrogen requires the knowledge of Dalton's law, the ideal gas law, and the molar masses of argon and hydrogen. Dalton's law of partial pressures states that the total pressure of a gas mixture is the sum of the pressures that each gas would exert if it were alone. The ideal gas law relates the pressure, volume, temperature and number of moles of a gas.
First, convert the volume of the mixture from liters to moles using the ideal gas law (PV = nRT) and obtain total moles of the mixture. Then, find out the total mass of argon and hydrogen in the mixture using their molar masses. Now, you will know the fraction of argon in the mixture (argon mass/total mass). Multiply this fraction by the total pressure to obtain the partial pressure of argon since by Dalton's law, total pressure is the sum of partial pressures.
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Predict whether or not a precipitate will form upon mixing 175.0 ml of a 0.0055 mkcl solution with 145.0 ml of a 0.0015 m agno3 solution. identify the precipitate, if any. express your answer as a chemical formula. enter noreaction if no precipitate is formed.
Answer:
AgCl
Step-by-step explanation:
The equation for a possible reaction is
KCl(aq) + AgNO₃(aq) ⟶ KNO₃ + AgCl
The possible precipitate is silver chloride.
=====
Moles KCl = 0.1750 × 0.0055/1
Moles KCl = 9.62 × 10⁻⁴ mol
Moles AgNO₃ = 0.1450 × 0.0015
Moles AgNO₃ = 2.18 × 10⁻⁴ mol
=====
Total volume = 175.0 + 145.0
Total volume = 320.0 mL
=====
[KCl] = 9.62 × 10⁻⁴/0.3200
[KCl] = 3.01 × 10⁻³ mol·L⁻¹
=====
[AgNO₃] = 2.18 × 10⁻⁴/0.3200
[AgNO₃] = 6.80 × 10⁻⁴ mol·L⁻¹
=====
The equation for the equilibrium is
AgCl ⇌ Ag⁺ + Cl⁻
I/mol·L⁻¹: 6.80 × 10⁻⁴ 3.01 × 10⁻³
Q_sp = [Ag⁺][Cl⁻]
Q_sp = 6.80 × 10⁻⁴ × 3.01 × 10⁻³
Q_sp = 2.04 × 10⁻⁶
K_sp = 1.8 × 10⁻¹⁰
Q_sp > K_sp, so a precipitate will form.
"[tex]Qsp>Ksp[/tex]" precipitate will form. A further explanation is below.
According to the question,
[tex]AgNO_3(aq) +KCl(aq) \rightarrow AgCl(s)+KNO_3(aq)[/tex]We can say the,
AgCl is a precipitate.
Ksp of AgCl,
[tex]1.8\times 10^{-10}[/tex]then,
→ [tex]Qsp = [Ag^+][Cl^-][/tex]
By substituting the values, we get
→ [tex]= 0.0015\times 0.0055[/tex]
→ [tex]= 8.25\times 10^{-6}[/tex]
Thus the above answer is appropriate.
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