Answer:
[tex]\boxed{2}[/tex]
Explanation:
Alkaline earth metals are in group 2. The number of valence electrons of elements in group 2 is 2.
2 valence electrons do the alkaline earth metals have. Therefore, option B is correct.
Alkaline earth metals are the elements in Group 2 of the periodic table, which includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).
In general, elements in Group 2 have two valence electrons. Valence electrons are the electrons located in the outermost energy level (or shell) of an atom. For the alkaline earth metals, the outermost energy level is the second energy level, which can hold up to 8 electrons.
Only the two electrons in the s sublevel of the second energy level are considered valence electrons. These two valence electrons are involved in chemical reactions and bonding.
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A current is induced in a wire by moving the wire through a magnetic field. Which is one factor that affects the direction of the current?
Answer:
One factor that affects that affects the direction of the current is the direction of motion of the wire
Explanation:
According to Fleming's right hand rule when a conductive wire which is within a circuit is moved through a magnetic field, due to Faraday's law of electromagnetic induction an electric current is induced in the wire such that the direction of motion of the wire, the direction of the magnetic field and the direction of the electric current are perpendicular to each other such that if the right hand has the thumb middle finger and the index finger held perpendicular to each other
The motion of the wire being in the direction of the wire
The first or index finger points in the direction of the magnetic field
The middle finger points in the direction of the induced electric current
Therefore, the direction of the the current depends on the direction of motion of the wire.
Help ya girl out plz
Answer:
The correct option is B
Explanation:
just did it edg 2020.
Answer:
the answer is c
Explanation:
In each of the following groups of substances, pick the one that has the given property. Justify your answer. a) highest boiling point: HBr, Kr, Cl2 b) highest freezing point: H2O, NaCl, Hf c) lowest vapor pressure at 25C: Cl2, Br2, I2 d) lowest freezing point: N2, CO, CO2 e) lowest boiling point: CH4, CH3CH3, CH3CH2CH3 f) highest boiling point: HF, HCl, HBr Could someone help me understand fully how to do this?
Answer:
A) HBr
b) NaCl
c) I2
d) N2
e) CH4
f) HF
Explanation:
a) HBr has the highest boiling point because its molecules are held by intermolecular hydrogen bonding unlike other compounds listed.
b) the freezing point of a substance is the same as its melting point. Ionic substances have the highest melting points. Hence NaCl has a melting (freezing) point of about 801°C
c) vapour pressure depends on molecular mass. The higher the molecular mass the lower the vapour pressure. I2 has the highest relative molecular mass and hence the lowest vapour pressure.
d) The molecule with the lowest molecular mass is expected to have the lowest intermolecular dispersion forces and hence the lowest freezing point.
e) Degree of dispersion forces and boiling point increases with increase in molecular mass. Since CH4 has the lowest molecular mass, it will also possess the lowest boiling point.
e) The magnitude of electro negativity decreases down the group. Hence, fluorine is the most electronegative element among the halogens. Hydrogen bonding results when hydrogen is covalently bonded to an electronegative element. The strength of the hydrogen bonding depends on the electro negativity of the electronegative element.
For hydrogen halides, HF has the highest boiling point since F is the most electronegative halogen and HF possess the greatest degree of hydrogen bonding among the hydrogen halides. Hydrogen bonding leads to increase in boiling point of substances.
The intermolecular forces in the compound have been responsible for the various properties of the compounds.
(a) Highest boiling point:
The hydrogen bonding has resulted from the electrostatic interaction of the H with the more electronegative atom. The strong interaction results in a higher boiling point.
HBr has consisted of the hydrogen bond, thus having the highest boiling point.
(b) Highest freezing point:
The higher hydrogen bonding in the structure results in a high freezing point. The ionic compounds with electrostatic interactions result in a high freezing point.
NaCl has been an ionic compound, thus has been consisted of the highest freezing point.
(c) Lowe vapor pressure:
Vapor pressure has been inversely proportional to the molecular mass. The higher the molecular weight, the lower has been the vapor pressure.
Iodine has the highest molecular weight, thereby has the lowest vapor pressure.
(d) Lowest freezing point:
Based on the molecular weight, the lower the molecular weight, the lower has been the freezing point of the molecule.
The [tex]\rm \bold{CH_4}[/tex] has the lowest molecular weight, thus the lowest freezing point.
(e) Highest boiling point:
The more electronegative atom in the hydrogen bonding, the higher has been the stability and the higher the boiling point.
HF has the highest boiling point as it has H bonded with the most electronegative element.
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Assertion: When a strong acid is added to a buffer system consisting of a weak acid (HA) and its conjugate base (A-), the concentration of the conjugate base increases. Reason: A stoichiometric amount of the weak acid is converted to its conjugate base. Group of answer choices
Answer:
Both the assertion and reason are false
Explanation:
A buffer is a solution that resists changes in acidity and alkalinity. When a solution is buffered, it pH can only vary within a small range. A buffer is made up of a weak acid/base and its salt.
When a strong acid is added to a buffer solution, the conjugate base will react with the H+ from the strong acid to form the undissociated weak acid HA as follows; H+(aq) + A- (aq)→ HA(aq). Hence, H+ concentration decreases owing to its reaction with the A- thus the pH changes only slightly.
At the time when the strong acid should be added so here Both the assertion and reason are false
What is buffer?It is a solution that resists changes with respect to the acidity and alkalinity. When a solution should be buffered, it pH can only change within a small range. At the time when a strong acid should be added to a buffer solution, the conjugate base should be react with the H+ from the strong acid to form the undissociated weak acid.
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Calculate the pH of a solution obtained by mixing 477 mL of 0.17 M hydrochloric acid with 253 mL of M lithium hydroxide. Assume the combined volume is the sum of the two original volumes.
Answer:
pH = 0.984
Explanation:
Molarity LiOH = 2.1x10⁻²M
HCl will react with LiOH as follows:
HCl + LiOH → H₂O + LiCl
1 moles of HCl reacts per mole of LiOH
Moles of each reactant in solution are:
HCl = 0.477L ₓ (0.17mol / L) = 0.08109 moles HCl
LiOH = 0.253L ₓ (2.1x10⁻² mol / L) = 5.313x10⁻³ moles of LiOH.
That means LiOH is the limiting reactant and excess moles of HCl that will remain in solution are:
0.08109 mol - 0.005313mol = 0.0758 moles HCl
As HCl dissociates in water as H⁺ and Cl⁻ ions, you will have in solution 0.0758 moles of H⁺
pH = -log [H⁺] and [H⁺] = moles H⁺ / L of solution.
Volume of the mixture in liters is: 0.477L + 0.253L = 0.730L.
That means [H⁺] is 0.0758 moles of H⁺ / 0.730L = 0.1038M
Replacing:
pH = -log [H⁺]
pH = -log [0.1038]
pH = 0.984(b) (i)
What is an ion?
(c)
Name two types of ions and state how they are formed
Types of ions:
Answer:
an atom or molecule with a net electric charge due to the loss or gain of one or more electrons
List at least four characteristics of acids
Answer:
pH>7
sour taste
donate H+ ions
turn litmus paper from blue to red
Explanation:
Answer:
Explanation:
pH < 7.
Sour taste (though you should never use this characteristic to identify an acid in the lab)
Reacts with a metal to form hydrogen gas.
Increases the H+ concentration in water.
Donates H+ ions.
Turns blue litmus indicator red.
Which element would have properties most similar to those of
cesium (Cs)?
O A. Rb
B. Ca
C. Sr
D. Ba.
Answer:
Rb
Explanation:
This is because they are in the same group which means they share similar properties.
What do rubidium and cesium have in common?
This family consists of the elements lithium, sodium, potassium, rubidium, cesium, and francium (Li, Na, K, Rb, Cs, and Fr, respectively). Group one elements share common characteristics.
What are the physical and chemical properties of caesium?
It is silvery gold, soft, and ductile. It is the most electropositive and most alkaline element.
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How can the rate constant be determined from the rate law
Answer: The rate constant is the reaction rate divided by the concentration terms.
Adrian loves the pancakes! The problem is, the recipe serves only six, and he has 540 people in his family (including aunts, uncles, and cousins). Now, he needs help increasing the recipe to feed his entire family. However, Adrian is particular - he insists on using only three significant figures with scientific notation.
Answer:
ingredient. U.s unit. SI unit. SI unit(540)
flour. 2cups. ²/6. 180cups = 1.8×10²
milk. 2cups. ²/6. 180cups. =1.8×10²
eggs. 2. ²/6. 180eggs. =1.8×10²
melted butter. ⅓cup ¹/18. 30cups. =3×10¹
sugar. 1spoon. ¹/6. 90spoons. =9×10¹
baking powder 2spoons ²/6. 180spoons. =1.8×10²
salt. ½spoon. ¹/12. 45spoons. =4.5×10¹
Explanation:
1) to get the SI unit divide the U.S unit by 6
example:eggs = 2÷6. =²/6
2) to get the SI unit for 540 people ,multiply the SI unit by 540.
example:eggs ²/6×540. = 180
3)convert the answers to scientific notation
example:eggs =180. =1.8×10²
Suppose you carry out a titration involving 3.00 molar HCl and an unknown concentration of KOH. To bring the reaction to its end point, you add 35.3 milliliters of HCl to 105.0 milliliters of KOH. What is the concentration of the KOH solution?
Answer: The concentration of the KOH solution is 1.01 M
Explanation:
According to neutralization law:
[tex]n_1M_1V_1=n_2M_2V_2[/tex]
where,
[tex]n_1[/tex] = basicity of [tex]HCl[/tex] = 1
[tex]n_2[/tex] = acidity of KOH = 1
[tex]M_1[/tex] = concentration of HCl = 3.00 M
[tex]M_2[/tex] = concentration of KOH = ?
[tex]V_1[/tex] = volume of HCl = 35.3 ml
[tex]V_2[/tex] = volume of KOH = 105.0 ml
Putting the values we get:
[tex]1\times 3.00\times 35.3=1\times M_2\times 105.0[/tex]
[tex]M_2=1.01[/tex]
Thus the concentration of the KOH solution is 1.01 M
The volume of a sample of pure HCl gas was 221 mL at 20°C and 111 mmHg. It was completely dissolved in about 50 mL of water and titrated with an NaOH solution; 18.7 mL of the NaOH solution was required to neutralize the HCl. Calculate the molarity of the NaOH solution.
Answer:
[tex]molarity =6.9\times 10^{-3}\ M\\[/tex]
Explanation:
We know that , the reaction of HCl and NaOH is given as follows
[tex]NaOH+HCl=NaCl +H_2O[/tex]
Given that
Pressure = 111 mm Hg
[tex]P=111\times 13.6\times 10^{-3}\times 9.81\times 1000=14.809\ kPa[/tex]
Temperature = 20°C
T=20+273=293 K
Volume= 221 m L
V=0.221 L
Number of moles of HCl is given as follows
[tex]n=\dfrac{P\times V}{R\times T}\\n=\dfrac{0.148\times 0.221}{0.821\times 293}=1.3\times 10^{-4}\ moles[/tex]
From the above reaction we can say that
Number of moles of HCl=Number of moles of NaOH
Volume of NaoH is given as follows
V=18.7 = 0.0187 L
Therefore molarity
[tex]molarity =\dfrac{n}{V_{NaOH}}\\molarity =\dfrac{1.3\times 10^{-4}}{0.0187}=6.9\times 10^{-3}\ M\\molarity =6.9\times 10^{-3}\ M\\[/tex]
Why do Group 12 elements have different properties than Group 13
elements?
A. They have different numbers of neutrons.
B. They have different numbers of valence electrons,
C. They have different numbers of protons.
D. They have different atomic numbers.
The group 12 elements have different properties than group 13 elements because both have different number of valence electron.
What is valence electron?The electron present in valence shell is called valence electron.
The electronic configuration group 12 and group 13 is given below.
Electronic configuration Group 12 = (n-1)d10 ns2
Electronic configuration Group 13 = ns2np1
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What is the concentration of a solution if 65 g of sugar is dissolved into 200 ml of water?
Answer: the concentration in g/L 325 while in molarity is 0.6398(M).
Answer:
325 g/L,
0.9503 M
Explanation:
65 g sugar --- 0.2 L
x g --- 1 L
x = 65/0.2 g/L = 325 g/L
Sugar(sucrose) is C12H22O11.
Molar mass (C12H22O11) = 12*12 + 1*22 + 16*11 = 342 g/mol
325 g/L * 1 mol/342 g = 0.9503 mol/L = 0.9503 M
Answer 0.6398(M) is not related to sugar (sucrose),
it should be given formula or molar mass of sugar if it is different than sucrose.
1) Determine a fórmula da base hidróxido de bário: * 1 ponto a) b) c) d) 2) As bases são substâncias iônicas, ou seja, quando são solubilizadas em água liberam íons, qual das características abaixo pode ser atribuída as soluções iônicas? * 1 ponto a) Conduzem corrente elétrica. B) Isolantes elétricos. C) Radioatividade. D) Emissão de raio UVA.
Answer:
1) Ba(OH)₂
2) The correct option is a) they conduct electricity.
Explanation:
To deduce the formula of Barium hydroxide, we have to go to the periodic table and look for the Barium (Ba), which is in group 2 and has an ionic charge of 2+. Hydroxides are not an element that is present in the periodic table is the combination of Oxygen and Hydrogen (OH), and its ionic charge is 1-.
To name this substance, we write the elements that form it, which are Ba OH, then we see the ionic charges that they have, Ba2+ OH 1- and we change these charges giving the 2+ to the OH and the 1- to the Ba. It would look Ba OH₂; we do not write the 1, and as there is a 2, the OH, has to be between brackets so that the final formula is Ba(OH)₂. What we did is balancing the charges of the elements. In other words, we need 2 OH for every Ba. Hydroxides give an electron to balance the Ba ionic charge.
Barium Hydroxide is an ionic compound because ionic compounds are formed by a metal (Ba) and a nonmetal element (OH), ionic compounds are charged, so when they are in an aqueous solution they conduct electricity because their ions move freely in the solution.
Which is described as the force holding two atoms together? Select one: a. cation b. chemical bond c. formula unit d. lattice
Answer:
The correct option is;
b.Chemical bond
Explanation:
Chemical bonds are the attractive forces holding the atoms within a compound together. The concept of chemical bonding is fundamental to the explanation of chemical phenomena including reaction mechanism and molecular behavior
There are different chemical bonds such as ionic bonds formed by the attraction of oppositely charged ions, covalent bonds, formed by the sharing of electrons and polar covalent bonds.
Why do group 12 elements have different properties than group 13 elements
Answer:
A
Explanation:
25. Which answer best describes the continental rise? area of land that drops toward deep ocean basins 75 mile shallow flat area just off coastlines thick deposits of sediments carried off of the shelf the surf area along coastlines
Answer:
Thick deposits of sediments carried off of the shelf
Explanation:
The continental rise is a thick deposit of sediments that accumulate between the continental slope and the abyssal plain
A is wrong. The area of land that drops toward the deep ocean basins is the continental slope.
B is wrong. The 75-mile shallow flat area just off coastlines is the continental shelf.
D is wrong. The surf area along coastlines is the surf zone .
Which statement is true about oxygen-17 and oxygen-18? A Their atoms have identical masses B They do not have the same number of protons C They have different numbers of electrons D They are isotopes of oxygen
Answer:
option d
Explanation:
isotope means atoms with different mass no. 17 and 18 written on the left represent mass number
this is because atoms can differ in mass no.
option a is incorrect as they have different mass no,hence,different massoption b is incorrect as atoms-oxygen-17 and oxygen 18-of same element oxygen cannot differ in no of protonsif they had different no of electons they would have a charge like -1,-2,etcoption d is correct,because atoms can differ in mass no. isotope means atoms with different mass no. 17 and 18 written on the left represent mass numberMatter is composed of exceedingly small particles called atoms. An atom is the
smallest unit of an element that can participate in a -------
Answer:
Matter is composed of exceedingly small particles called atoms. An atom is the
smallest unit of an element that can participate in a chemical reaction.
Answer:
Chemical reaction.
Explanation:
To change from tens to hundreds, you multply by
Answer:
10
Explanation:
Example:
10 · 10 = 100
60 · 10 = 600
Answer:
you multiply by 10.
Explanation:
10 - the one is in the thenth place
10 * 10 = 100 - the one is in the hundreth place
20 - the two is in the thenth place
20 * 10 = 200 - the two is in the hundreth place
in terms of bonds, what would the molecule C3H6 be classified as
Explanation:
Cyclopropane is a cycloalkane conposed of three carbon atoms to form a ring. It has a rols as an inhalation anaesthetic. It is a cycloalkane and a member of cyclopropanes.
Answer:
Alkane
Explanation:
in which sphere does a dolphin swim A. hydrosphere B. atmosphere C. magnetosphere D. lithosphere
Answer:
A. Hydrosphere
Explanation:
Hydro means water and dolphins swim in water.
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Identify the type of reaction in the following and define each of them. (i) Carbohydrates are broken down to form glucose. (ii) Tarnishing of copper. (iii) Heating of ferric oxide with aluminium powder. (iv) Blue colour of copper sulphate solution disappears when zinc dust is added to it. (v) Dilute sulphuric acid is adeed to sodium hydroxide solution .
Answer:
(i) hydrolysis; (ii) combination; (iii) single replacement;
(iv) single replacement; (v) double replacement
Explanation:
(i) Carbohydrates are broken down to form glucose
Carbohydrates must react with water to form glucose.
For example,
C₆H₁₁O₅-O-C₆H₁₁O₆ + H-O-H ⟶ 2C₆H₁₂O₆
maltose glucose
This is a hydrolysis reaction — the reaction of a compound in which a molecule of water breaks one or more bonds to form new substances.
The reaction is not a decomposition (a reaction in which a compound breaks down into two or more simpler substances), because two different molecules are involved.
(ii) Tarnishing of copper.
Cu + S ⟶ CuS
This is a combination or synthesis reaction — in which two or more substances combine to form a single new substance.
(iii) Heating of ferric oxide with aluminium powder
Fe₂O₃ + 2Al ⟶ Al₂O₃ + 2Fe
This is a single displacement or single replacement reaction — in which one element replaces another element in a compound.
Here, Al is replacing Fe in its oxide.
(iv) Blue colour of copper sulphate solution disappears when zinc dust is added to it
CuSO₄ + Zn ⟶ ZnSO₄ + Cu
This is a single displacement or single replacement reaction.
Here, Zn is replacing Cu in its sulfate.
(v) Dilute sulfuric acid is added to sodium hydroxide solution
H₂SO₄ + 2NaOH ⟶ Na₂SO₄ + 2H₂O
2H⁺, SO₄²⁻ + 2Na⁺OH⁻ ⟶ 2Na⁺, SO₄²⁻ + 2H-OH
This is a double displacement or double replacement reaction — in which the positive and negative ions of two ionic compounds exchange places to form two new compounds.
The Na⁺ ions are replacing the H⁺ ions in the sulfuric, forming sodium sulfate and water,
Which condition must be met in order for an equation to be balanced? The elements in the reactants are the same as the elements in the products. There are fewer elements in the reactants than there are in the products. The number of atoms in the reactants is greater than the number of atoms in the products. The number of atoms in the reactants equals the number of atoms in the products.
Answer:
The number of atoms in the reactants equals the number of atoms in the products.
Explanation:
In every chemical reaction equation there are two sides; the reactants sides and the products side. The reactants side shows the species that combine to form the products. On both sides of the reaction equation, chemical species are found to be composed of atoms.
The major principle in balancing of chemical reaction equations is that the number of atoms of each element in the reactants side must be equal to the number of atoms of the same element on the products side. Once this condition is achieved, we can now say that the chemical equation is balanced.
Answer:
Answer D: The number of atoms in the reactants equals the number of atoms in the products.
Explanation:
Had the answer plus doing the quiz right now and got it right 100%
Answer the following questions: On a 10-fold dilution of a weak acid, the pH will ______________ . On a 10-fold dilution of a weak base, the pH will ______________. If one adds a very small amount of strong base to a buffered solution, the pH will _______________. Can you make a buffer using a strong acid
Answer:
i) increase
ii) decrease
iii) remain the same
iv) No, because it dissociates completely.
Explanation:
On a 10-fold dilution of a weak acid, the pH will increase because the concentration of hydrogen ions will decrease thereby increasing the pH to close to that of water.
On a 10-fold dilution of a weak base, the pH will decrease due to the removal of hydroxide ions from the solution. This results in the solution having a H closer to that of water.
If one adds a very small amount of strong base to a buffered solution, the pH will remain constant because a buffer solution acts to withstand any change to its pH on the addition of small quantities of either an acid or a base.
A buffer solution cannot be made with a strong acid because thy undergo complete dissociation. Therefore, any small addition of base or acid will result in very large changes in the pH of the solution. A buffer solution is made with a weak acid and its conjugate base or a weak base and its conjugate acid.
144g of KCl dissolved in 1000cm3of water at 90oC. Calculate the solubility of KCl at this temperature. (K=39, Cl=35.5, 1dm3=1000cm3).
Answer:
The solubility of KCl is 1.93 mol/dm³
Explanation:
The information given are;
The mass of the potassium chloride, KCl = 144 g
The volume of the water solvent = 1000 cm³ = 1 dm³
The temperature of the solvent = 90 °C
The atomic mass of potassium, K = 39 u
The atomic mass of chlorine, Cl = 35.5 u
The number of moles of potassium in one mole of potassium chloride, KCl = 1 mole
The number of moles of chlorine in one mole of potassium chloride, KCl = 1 mole
The molar mass of the potassium chloride = 39 + 35.5 = 74.5 g/mol
The number of moles, n, of potassium chloride, KCl in 144 g of potassium chloride, KCl is given as follows
n = Mass/(Molar mass) = 144/74.5 = 1.93 moles
1.93 moles will dissolve in 1 dm³
Therefore, the solubility of KCl is 1.93 mol/dm³.
A 25.0 mL sample of a solution of an unknown compound is titrated with a 0.115 M NaOH solution. The titration curve above was obtained with pH at equivalence point of around 8. The unknown compound is ________.
Answer:
Weak acid
Explanation:
A titration curve is a graphical description of the change in pH of the solution in the conical flask as the reagent is added from the burette. A titration curve can be plotted for the different kinds of acid and base titrations. The volume of the titrant is always plotted as the independent variable and the pH of the solution as the dependent variable. The equivalence point is read off from the titration curve. A titration curve is very important because it shows the pH at various points during the titration.
A weak acid/strong base titration leads to an equivalence point above 7. From the question, we were told that the pH at equivalence point lies around 8. Hence the unknown substance must be a weak acid.
Which property would cesium most likely have?
Answer: The property that cesium most likely would have is being ductile (able to be deformed without losing toughness) due it being a very soft, alkali metal which has a very low melting point of 83.3 °F or 28.5 °C
Answer:
The answer is B. Ductile.
Explanation: Cesium belongs to a category of metals. They are often silver, fairly soft, and very ductile. The answer is right on edge 2020.
what reaction type is solid sodium bicarbonate + acetic acid?
Answer:
the neutralization reaction occurs