Explanation:
1. As you go across a period, what is a useful comparison point?
A.
oxides
2. Most elements are
A.
allotropes
3. A metalloid is a(n) __ conductor of heat and electricity than a metal.
A.
better
4. What causes the formation of allotropes?
A.
pressure
As you move __and __ elements become more metallic.
A.
left, down
5. All of the following metalloids form allotropes except
A.
B
6. What is a chemical property of a metal?
A.
malleable
Atoms of element X have 12 times the mass of atoms of oxygen, and atoms of oxygen have 16 times the mass of atoms of hydrogen. What is the mass of atoms of element X on a scale on which atoms of hydrogen have a mass of 1?
A. 16/12
B. 12/16
С. 12 x 16
D. 16-12
E. 1216
Answer:
C. 12 × 16
Explanation:
Let mH be the mass of atoms of hydrogen and mO be the mass of atoms of oxygen. The atoms of oxygen have 16 times the mass of atoms of hydrogen. That is,
mO = 16 mH [1]
Let mX be the mass of the atoms of X. Atoms of element X have 12 times the mass of atoms of oxygen. That is,
mX = 12 mO [2]
If we substitute [1] in [2], we get
mX = 12 × 16 mH
If mH is 1, we get,
mX = 12 × 16 × 1
mX = 12 × 16
The strongest base that can exist in a solution in appreciable concentration is the conjugate base of the solvent.
a. True
b. False
Answer:
a. True
Explanation:
From the basic concepts of acids and bases, we know that when a base accepts a hydrogen ion (H⁺), it forms a conjugate acid which can accept again the H⁺ ion:
B⁻ + H₂O ⇆ BH + OH⁻
The stronger the base, the weaker the conjugate base. Thus, as more strength has a base, lesser strength will have the conjugate base (it will not be able to accept again the H⁺ ion). For example, when water (H₂O) loses its H⁺ , it forms the conjugate base OH⁻. So, OH⁻ is the stronger base that can exist in an aqueous solution.
H₂O ⇆ H⁺ + OH⁻
In fact, strong bases are hydroxides, such as NaOH or KOH.
Match each description below:
a. Will react with water.
b. Will react with steam or acid, but not water.
c. Will react with acid only
d. Will not tract with water, steam, or acid.
1. Cr
2. Cu
3. K
d. Sn
Answer:
a) will react with water: K
b) will react with steam or acid, but not water: Cr & Sn
d) will not react with water, steam, or acid: Cu
Explanation:
K reacts violently with water.
Cr will react with steam to form an oxide + H gas and will react with most acids
Sn will react with steam to form SnO₂ + H gas and, though it does not react as rapidly as other metals in acid, it dissolves easily in concentrated acids
Cu is an extremely nonreactive metal, which is what makes it so suitable for wiring
Identify the isoelectronic elements.
i. Cl-, F-, Br-, I-, At-
ii. Ne, Ar, Kr, Xe, He
iii. N3-, S2-, Br-, Cs+, Sr2+
iv. N3-, O2-, F-, Na+, Mg2+
v. Li+, Na+, K+, Rb+,Cs+
Answer:
iv. N³⁻, O²⁻, F⁻, Na⁺, Mg²⁺
Explanation:
Isoelectronic elements are those that have the same number of electrons. So, if at least 2 elements differ in their number of electrons, the series is not of isoelectronic elements.
To know the number of electrons we will consider the atomic number and add electrons if it is an anion and subtract electrons it is a cation.
Identify the isoelectronic elements.
i. Cl⁻, F⁻, Br⁻, I⁻, At⁻. NO. Cl⁻ has 18 electrons (17+1) and F⁻ has 10 electrons (9+1). ii. Ne, Ar, Kr, Xe, He. NO. Ne has 10 electrons and Ar has 18. iii. N³⁻, S²⁻, Br⁻, Cs⁺, Sr²⁺. NO. N³⁻ has 10 electrons (7+3) and S²⁻ has 18 (16+2).iv. N³⁻, O²⁻, F⁻, Na⁺, Mg²⁺. YES. They all have 10 electrons v. Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺. NO. Li⁺ has 2 electrons (3-1) and Na⁺ has 10 (11-1).A buffer solution contains 0.298 M ammonium chloride and 0.478 M ammonia. If 0.0560 moles of hydroiodic acid are added to 225 mL of this buffer, what is the pH of the resulting solution?
Answer:
pH = 8.87
Explanation:
Hydroiodic acid, HI, is a strong acid that reacts with ammonia, NH3, to produce ammonium ion, NH⁴⁺. That means the moles of HI added = moles of NH3 consumed and moles of NH4⁺ produced.
Initial moles NH₄⁺:
0.225L * (0.298mol/L) = 0.06705 moles
Initial moles NH3:
0.225L * (0.478mol/L) = 0.10755 moles
After the reaction the moles are:
0.10755moles NH3 - 0.0560moles = 0.05155 moles NH3
0.06705moles NH4+ + 0.0560moles = 0.12305 moles NH4+
Using H-H equation for weak bases:
pOH = pKb + log ([NH4+] / [NH3])
pKb for ammonia is 4.75, [NH4+] could be the moles of NH4+ = 0.12305mol,
[NH3] = 0.05155moles
Replacing:
pOH = 4.75 + log (0.12305mol / 0.05155moles)
pOH = 5.13
pH = 14-pOH
pH = 8.87explain why seeing a gas doesn not always indicate that there was a chemical change.
A series of measurements in the lab led to an experimental result of 32.9 mL, with a calculated standard deviation of 0.3 mL. What is the standard way to report this result?
Answer: The standard way to report this result is [tex]32.9\pm 0.3 mL[/tex]
Explanation:
The standard method of representing a result is:
[tex]\text{Calculated value }\pm \text{ Standard deviation}[/tex]
The reporting of a result is done in correct significant figures.
We are given:
Calculated value = 32.9 mL
Standard deviation = 0.3 mL
Rule of significant figures applied when numbers are added or subtracted:
The number having less number of significant figures after the decimal point will determine the number of significant figures in the final answer.
Number of significant figures after the decimal point = 1
Hence, the standard way to report this result is [tex]32.9\pm 0.3 mL[/tex]
At 35°C, K = 1.6 × 10^-5 for the reaction
2 NOCl(g) ⇌ 2 NO(g) + Cl2(g)
Calculate the concentrations of all species at equilibrium for each of the following original mixtures.
a. 2.0 mol pure NOCl in a 2.0 L flask
b. 2.0 mol NOCl and 1.0 mol Cl2 in a 1.0 L flask
Answer:
a) [NOCl] = 0.968 M
[NO] = 0.032M
[Cl²] = 0.016M
b) [NOCl] = 1.992M
[NO] = 0.008 M
[Cl2] = 1.004 M
Explanation:
Step 1: Data given
Temperature = 35°C = 308K
K = 1.6 × 10^-5
Step 2: The reaction
2 NOCl(g) ⇌ 2 NO(g) + Cl2(g)
For 2 moles NOCl we'll have 2 moles NO and 1 mol Cl2
Step 3
a. 2.0 mol pure NOCl in a 2.0 L flask
Concentration at the start:
Concentration = mol / volume
[NOCl] = mol / volume
[NOCl] = 2.0 / 2.0 L
[NOCl] = 1.0 M
[NO] = 0 M
[Cl] = 0M
Concentration at the equillibrium
[NOCl] = 1.0M - 2x
[NO] = 2x
[Cl2]= x
K = [Cl2][NO]² / [NOCl]² = 1.6*10^-5
1.6*10^-5 = ((2x)² * x) / (1.0-2x)²
x = 0.016
[NOCl] = 1.0 - 2*0.016 = 0.968 M
[NO] = 2*0.016 = 0.032M
[Cl²] = 0.016M
b. 2.0 mol NOCl and 1.0 mol Cl2 in a 1.0 L flask
Concentration at the equillibrium
[NOCl] = 2.0 mol / 1.0 L = 2.0 M
[NO] = 0 M
[Cl2]= 1.0 mol / 1.0 L = 1.0 M
Concentration at the equillibrium
[NOCl] = 2.0M - 2x
[NO] = 2x
[Cl2]= 1.0 + x
K = [Cl2][NO]² / [NOCl]² = 1.6*10^-5
1.6 *10^-5 = (2x)²*(1.0+x) / ((2.0-2x)²)
1.6 *10^-5= (2x)² * 1 )/2.0²
1.6 *10^-5= 4x² / 4 = x²
x = [tex]\sqrt{1.6 *10^-5}[/tex] = 4.0*10^-3
[NOCl] = 2.0 - 2*0.004 = 1.992M
[NO] = 2*0.004 = 0.008 M
[Cl2] = 1+ 0.004M = 1.004 M
You decide to share some sugar sweetened fruit juice with your friend. You divide the fruit equally into two glasses. Then an additional equal volume of water is added to glass 1. Which glass would have the lower molarity?
Answer:
Glass 1
Explanation:
Molarity is measured in moles of substance per liter.
For the sake of calculations, let's say that each glass contains 1 mole of juice and 1 liter after it is divided between the glasses. If you add an equal amount of water to glass 1 ( another liter), you now have:
Glass 1 = 1 mole / 2 liters = 0.5 M
Glass 1 = 1 mole/ 1 liter = 1 M
So glass 1 will have a lower molarity
how many moles of neon gas have a volume of 0.84 L and a pressure of 4.6 atm at 222k
Answer:
n = 0.21 moles
Explanation:
Given that,
Volume, V = 0.84 L
Pressure, P = 4.6 atm
T = 222 K
We need to find the number of moles of Neon gas. We know that,
PV = nRT
Where
n is the number of moles
R i the gas constant, R = 0.08206 L-atm/mol-K
Put all the values,
[tex]n=\dfrac{PV}{RT}\\\\n=\dfrac{4.6\times 0.84}{0.08206 \times 222}\\\\n=0.21\ \text{moles}[/tex]
So, there are 0.21 moles of Neon gas.
Place the following in order of increasing molar entropy at 298 K.
a. C3H8 < SO < CO2
b. CO2 < C3H8 < SO
c. C3H8 < CO2 < SO
d. SO < CO2 < C3H8
e. CO2 < SO < C3H8
Answer:
SO < CO2 < C3H8
Explanation:
Entropy refers to the degree of disorderliness of a system. The standard molar entropy of a substance refers to the entropy of 1 mole of the substance vunder standard conditions.
The molar entropy depends on the number of microstates in the system which in turn depends on the number of atoms in the molecule.
C3H8 has 11 atoms and hence the highest number of microstates followed by CO2 having three atoms and least of all SO having only two atoms.
What is the observation of heating of iodine crystals
Answer:
On heating, the van der Waals dispersion forces existing then will easily break as it has a low boiling point and sublimates into gas. On heating iodine in the test tube, iodine evolves as violet fuming gas.
Explanation:
Predict the products from theses reaction, and balance the equations. Include phase symbols.
Reaction : K(s)+Cl2(g)⟶
Reaction :Cu(s)+O2(g)⟶
Answer:
2 K(s) + Cl₂(g) ⟶ 2 KCl(s)
2 Cu(s) + O₂(g) ⟶ 2 CuO(s)
Explanation:
Both reactions are synthesis reactions (two substances combine to form another).
Reaction: K(s) + Cl₂(g) ⟶
The product is the binary salt KCl. The balanced chemical equation is:
2 K(s) + Cl₂(g) ⟶ 2 KCl(s)
Reaction: Cu(s) + O₂(g) ⟶
The most likely product is the metal oxide CuO. The balanced chemical equation is:
2 Cu(s) + O₂(g) ⟶ 2 CuO(s)
For the iron thiocyanate system, what is the value of the equilibrium constant, Kc, if the following are the concentrations of all species present. Provide your answer to three digits after the decimal.
FeSCN2+ 0.501
Fe3+ 0.494
SCN- 0.639
Answer:
Kc = 0.630
Explanation:
The equilibrium of the thiocyanate system occurs as follows:
FeSCN²⁺(aq) ⇄ Fe³⁺(aq) + SCN⁻(aq)
And equilibrium constant, kc, is:
Kc = [SCN⁻] [Fe³⁺] / [FeSCN²⁺]
Replacing with the gven concentrations:
Kc = 0.639M*0.494M / 0.501M
Kc = 0.630An aqueous solution containing 5.72 g
of lead(II) nitrate is added to an aqueous solution containing 5.85 g
of potassium chloride. The reaction goes to completion, but some was lost in the process of washing and drying the precipitate. The percent yield for the reaction is 81.9%
. How many grams of precipitate is recovered? How many grams of the excess reactant remain? Assume the reaction goes to completion.
Answer:
3.93g are recovered
Explanation:
Pb(NO3)2 reacts with KCl as follows:
Pb(NO3)2 + 2KCl → 2KNO3 + PbCl2
To solve this question we need to find the moles of each reactant in order to find the limiting reactant:
Moles Pb(NO3)2 -Molar mass: 331.2 g/mol-
5.72g * (1mol/331.2g) = 0.01727 moles
Mole KCl -Molar mass: 74.5513g/mol-
5.85g * (1mol/74.5513g) = 0.07847 moles
For a complete reaction of 0.07847 moles of KCl are required:
0.07847 moles KCl * (1mol Pb(NO3)2 / 2mol KCl) = 0.03923 moles Pb(NO3)2
As there are just 0.01727 moles, Pb(NO3)2 is limiting reactant. Assuming 100% of yield:
Moles PbCl2 = Moles Pb(NO3)2
Mass PbCl2 -Molar mass: 278.1g/mol-
0.01727 moles * (278.1g / mol) = 4.80g
As percent yield is 81.9% = 0.819, the mass of PbCl2 recovered was:
4.80g * 0.819 = 3.93g are recovered
Compare the solubility of calcium sulfite in each of the following aqueous solutions:
a. 0.10 M Ca(CH3COO)2
b. 0.10 M K2SO3
c. 0.10 M NaNO3
d. 0.10 M KCH3COO
1. More soluble than in pure water.
2. Similar solubility as in pure water.
3. Less soluble than in pure water.
Answer:
0.10 M Ca(CH3COO)2- Less soluble than in pure water.
0.10 M K2SO3- Less soluble than in pure water.
0.10 M NaNO3 - More soluble than in pure water.
0.10 M KCH3COO- Similar solubility as in pure water.
Explanation:
We have to cast our minds back to the idea of common ions effect. If any ion is already present in solution, the presence of that ion in solution prevents any solute containing a common ion with the solution from dissolving in that solution. In order words, the presence of a common ion makes a solute less soluble in a solvent than it is in pure water.
For instance, 0.10 M Ca(CH3COO)2 and K2SO3 both contain Ca^2+ and SO3^2- ions respectively which are also contained in the solute calcium sulfite.
The presence of these common ions in solution makes calcium sulfite less soluble in these solutions than it is in pure water because the equilibrium position for the dissolution of the solute lies towards the left hand side.
However, calcium sulfite is more soluble in 0.10 M NaNO3 than in pure water due to displacement reaction between the ions in solution.
The solubility of calcium sulfite and 0.10 M KCH3COO in pure water is quite comparable.
13. The attraction between water molecules and an Na+
ion or a Cl- ion occurs because water molecules are
A) linear
B) symmetrical
C) polar
D) nonpolar
Answer:
C) Polar
Explanation:
The correct answer is polar
The attraction of sodium and chloride ions by the water is mediated by the polar nature of water. Thus, option C is correct.
What is polarity?The polarity is given as the formation of the partial positive and negative charge over the species in the ionization process.
Water molecule is having one hydrogen bounded with 2 oxygen atoms, and oxygen being more electronegative develops a partial negative charge, while hydrogen develops a partial positive charge.
The positive charge hydrogen and the negative charge oxygen attracts the opposite charge sodium and chloride ions. Thus, the attraction is mediated due to the polar nature of water. Hence, option C is correct.
Learn more about polarity, here:
https://brainly.com/question/3184550
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Can the properties of different substances in a mixture be used to separate them?
Answer: here you go
Explanation:
Physical properties of the substances in a mixture are different, so this allows the substances to be separated. Think about the example of a mixture of salt water.
Answer:
Mixtures can be classified on the basis of particle size into three different types: solutions, suspensions, and colloids. The components of a mixture retain their own physical properties. These properties can be used to separate the components by filtering, boiling, or other physical processes.
Explanation:
what would be the mass of 44.8 L of CO2 gas at STP?
show work if possible
Answer:
[tex]m=88.02g[/tex]
Explanation:
Hello there!
In this case, for this ideal gas law problem, it turns out necessary for us to remember that one mole of any gas is contained in 22.4 L at STP and therefore, we can use the following ratio to calculate the moles in 44.8 L of CO2:
[tex]\frac{1mol}{22.4L} =\frac{x}{44.8L}\\\\x= \frac{1mol*44.8L}{22.4L}=2mol[/tex]
Finally, since the molar mass of CO2 is 44.01 g/mol, we calculate the mass as follows:
[tex]m=2mol*\frac{44.01g}{1mol}\\\\m=88.02g[/tex]
Regards!
Identify the Lewis acid and Lewis base from among the reactants in each of the following equations.
Part A
Ag+(aq)+2NH3(aq)⇌Ag(NH3)2+(aq)
a. Ag+ is the Lewis acid and NH3 is the Lewis base.
b. Ag+ is the Lewis base and NH3 is the Lewis acid.
Part B
AlBr3+NH3⇌H3NAlBr3
a. AlBr3 is the Lewis base and NH3 is the Lewis acid.
b. AlBr3 is the Lewis acid and NH3 is the Lewis base.
Part C
Cl−(aq)+AlCl3(aq)⇌AlCl4−(aq)
a. AlCl3 is the Lewis acid and Cl− is the Lewis base.
b. AlCl3 is the Lewis base and Cl− is the Lewis acid.
Answer:
Part A
Ag+ is the Lewis acid and NH3 is the Lewis base.
Part B
AlBr3 is the Lewis acid and NH3 is the Lewis base.
Part C
AlCl3 is the Lewis acid and Cl− is the Lewis base.
Explanation:
A Lewis acid is any specie that accepts a lone pair of electrons. Ag^+, AlBr3 and AlCl3 all accepted lone pairs of electrons according to the three chemical reaction equations shown. Hence, they are Lewis acids.
A Lewis base donates a lone pair of electrons. They include neutral molecules having lone pair of electrons such as NH3 or negative ions such as Cl- .
Soda contains phosphoric acid (H3PO4). To determine the concentration of phosphoric acid in 50.0 mL of soda, the available phosphate ions are precipitated with excess silver nitrate as silver phosphate (418.58 g/mol). The dry Ag3PO4 is found to have a mass of 0.0576 g. What is the concentration of phosphoric acid in the soda?
Answer:
0.0270w/v% H3PO4 in the soda
Explanation:
All phosphates reacts producing Ag3PO4. To solve this question we must convert the mass of Ag3PO4 to moles. These moles = moles of H3PO4. We can find, thus, the mass of H3PO4 and the w/v% as follows:
Moles Ag3PO4 -Molar mass: 418.58g/mol-
0.0576g * (1mol / 418.58g) = 1.376x10⁻⁴ moles Ag3PO4 = moles H3PO4
Mass H3PO4 -Molar mass: 97.994g/mol-
1.376x10⁻⁴ moles Ag3PO4 = moles H3PO4 * (97.994g/mol) = 0.0135g H3PO4
w/v%:
0.0135g H3PO4 / 50.0mL * 100 =
0.0270w/v% H3PO4 in the sodaDuring a chemical reaction, an iron atom became the ion Fe2+. What happened to the iron atom?
Explanation:
Iron atom is been oxidised as it losses 2 electron to form 2 + ion.
What would happen to the Earth's hydrosphere if there were no atmosphere?
Sodium is a highly reactive metal and
chlorine is a toxic gas, but when they
come together the resulting material,
sodium chloride, is essential for life.
Which of the following is true when
sodium and chlorine are brought into
contact with one another?
Answer:
NaCl
Explanation:
[tex]na + cl > nacl[/tex]
This is also a salt
How do we fix climate change?
The biggest problem of course is conspiracy theorys. Some say it is just a hoxe when really their chidrin or grandchidrin will sufer greatly from it. How do we educate ourselfs better?
Answer:
Hi so your answer is that to helping fix the climate change you have to : speak up , power your home with renewable engery , reduce water waste , dont waste food , and finally invest energy .
Explanation:
Really hope i helped , have a nice day :)
Answer:
we can reduce air pollution,which is one of the main cause of climate change.Climate change is not a hoxe if it is not attending the upcoming generations will suffer greatly.
describe how lyophobic sols are synthesize by dispersion method
Explanation:
For preparing lyophobic sol, the substance in bulk is broken down into particles of colloidal dimensions (Dispersion) or aggregating smaller particles into particles of colloidal dimensions (condensation).
In an experiment, you added a base, NaOH, one mL at a time to 50 mL acetate buffer and recorded the pH. For the first 6 mL NaOH the pH increased from 4.5 to 4.9. At the 7th mL the pH was 6.6 and by the 8th mL the pH was 10.7. Knowing what you do about titrating acetate buffer with acid, is this experimental result what you expected or is it not expected
Answer:
yes the experimental result is the expected result .
Explanation:
When Titrating acetate buffer with acid the PH will decrease gradually from a more neutral PH to a more acidic level and this is because buffer solutions are prepared with weak acids and its conjugate base.
The results gotten from the continuous addition of base NaOH to the acetate buffer is the expected result because the base is been absorbed by the buffer solution and it is converted to a conjugate base of the buffer solution which will gradually increase the PH level of the solution as more conjugate base is formed due to the addition of more NaOH.
What is the difference between a physical change and a chemical change. Give an example of each.
Answer:
A physical change is a change in form.
A Chemical change is a change in materials.
Explanation:
Example of a physical change would be an ice cube meting.
Example of a chemical change would be mixing food coloring into a cup of water.
Which best expresses the uncertainty of the measurement 32.23 cm?
A.) ±0.05 cm
B.) 0.1 cm
C.) 1%
D.) ±0.01 cm?
Answer:
D.) ±0.01 cm?
Explanation:
Since 32.23 cm has two decimal places, the uncertainty is taken as one-half the last decimal pace.
The last decimal place is 0.03. Half of this is 0.03 cm/2 = 0.015 cm.
Since we cannot go below two decimal places, we ignore the 5 in 0.015 cm.
So, we have our uncertainty as 0.01 cm.
So, the best expression of the uncertainty in the measurement 32.23 cm is ± 0.01 cm.
So, the answer is D. which is ± 0.01 cm.
g Suppose you are titrating vinegar, which is an acetic acid solution of unknown concentration, with a sodium hydroxide solution according to the equation H C 2 H 3 O 2 + N a O H ⟶ H 2 O + N a C 2 H 3 O 2 If you require 30.01 mL of 0.1798 M N a O H solution to titrate 10.0 mL of H C 2 H 3 O 2 solution, what is the molar concentration of acetic acid in the vinegar? Type answer:
Answer: The molar concentration of acetic acid in the vinegar is 0.539 M.
Explanation:
The formula used is:
[tex]M_1V_1=M_2V_2[/tex]
where,
[tex]M_1[/tex] and [tex]V_1[/tex] are the concentration and volume of base.
[tex]M_2[/tex] and [tex]V_2[/tex] are the concentration and volume of an acid.
Given:
Molar concentration of NaOH = 0.1798 M
Volume of NaOH = 30.01 mL
Volume of acetic acid = 10.0 mL
Now putting all the given values in the above formula, we get:
[tex]M_1V_1=M_2V_2\\\\0.1798M\times 30.01mL=M_2\times 10.0mL\\\\M_2=0.539M[/tex]
Thu, the molar concentration of acetic acid in the vinegar is 0.539 M.
