The limestone used in building the Egyptian pyramids was used because it is _____________
O soft and sticky
O easily melted
O hard and brittle
Answer:
hard and brittle
hope this helps you ☺️☺️
good night take care sweet dream
How many moles is 1.80 * 10^24 molecules of H2O?
Answer:
3.0 molesExplanation:
To find the number of moles in a substance given it's number of entities we use the formula
[tex]n = \frac{N}{L} \\ [/tex]
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question we have
[tex]n = \frac{1.8 \times {10}^{24} }{6.02 \times {10}^{23} } = 2.990.. \\ [/tex]
We have the final answer as
3.0 molesHope this helps you
A 31.25 mL aliquot of weak base that has a concentration of 0.683 M will be titrated with 0.434 M HCl. Calculate the pH of of the solution upon neutralization of half of the weak base. The Kb of the base is 1.5×10-6.
Answer:
pH = 8.18
Explanation:
The weak base, X, reacts with HCl as follows:
X + HCl → HX⁺ + Cl⁻
Where 1 mole of X with 1 mole of HCl produce 1 mole of HX⁺ (The conjugate acid of the weak base).
Now, using H-H equation for bases:
pOH = pKb + log [XH⁺] / [X]
Where pOH is the pOH of the buffer (pH = 14 -pOH)
pKb is -log Kb = 5.824
And [X] [HX⁺] are the molar concentrations of each specie
Now, at the neutralization of the half of HX⁺, the other half is as X, that means:
[X] = [HX⁺]
And:
pOH = pKb + log [HX⁺] / [X]
pOH = 5.824 + log 1
pOH = 5.824
pH = 14-pOH
pH = 8.18Which ecosystem is the least stable?
A. A rain forest
B. A cornfield
C. A savanna
D. A coral reef
Which of the solids in the following set should you test to investigate for the effects of ANIONS on pH? Will give brainliest
-KClO
-RbF
-AlBr3
-Rb2SO3
-CrCl3
Answer:
KCIO
Explanation:
the only reason is because I looked online and the meaning for that is potassium hypochlorite my guy so if this is not right then I'm sorry but good luck.
How many moles of argon gas would be present in a 37.0 liter vessel at 45.00 °C at a pressure of 2.50 atm?
Answer:
3.54 mol
Explanation:
Step 1: Given data
Volume (V): 37.0 LTemperature (T): 45.00 °CPressure (P): 2.50 atmStep 2: Convert "T" to Kelvin
We will use the following expression.
K = °C + 273.15
K = 45.00°C + 273.15 = 318.15 K
Step 3: Calculate the number of moles (n) of argon gas
We will use the ideal gas equation.
P × V = n × R × T
n = P × V/R × T
n = 2.50 atm × 37.0 L/(0.0821 atm.L/mol.K) × 318.15 K = 3.54 mol
If 0.8675 g of KHP requires 24.56 mL of an NaOH solution to reach the equivalence
point in the titration, what is the concentration of the NaOH?
Answer:
[tex]M_{base}=0.173M[/tex]
Explanation:
Hello there!
In this case, since the titration of acids like KHP with bases like NaOH are performed in a 1:1 mole ratio, it is possible for us to know that their moles are the same at the equivalence point, and the concentration, volume and moles are related as follows:
[tex]n_{acid}=M_{base}V_{base}[/tex]
Thus, by solving for the volume of the base as NaOH, we obtain:
[tex]M_{base}=\frac{n_{acid}}{V_{base}} \\\\M_{base}=\frac{0.8675g*\frac{1mol}{204.22g} }{0.02456L} \\\\M_{base}=0.173M[/tex]
Best regards!
What is the correct coefficient for Fe2O3 in the balanced version of the following equation?
Fe2O3 + 3H2 → 2Fe + 3H2O
__Fe2O3+3H2→2Fe+3H2O
Answer:
The coefficient of Fe₂O₃ is 1
Explanation:
__Fe₂O₃ + 3H₂ —> 2Fe + 3H₂O
To know the correct coefficient of Fe₂O₃, we shall balanced the equation. This can be obtained as follow:
Fe₂O₃ + H₂ —> Fe + H₂O
There are 2 atoms of Fe on the left side and 1 atom on right side. It can be balance by writing 2 before Fe as shown below:
Fe₂O₃ + H₂ —> 2Fe + H₂O
There are 3 atoms of O on the left side and 1 atom on the right side. It can be balance by writing 3 before H₂O as shown below:
Fe₂O₃ + H₂ —> 2Fe + 3H₂O
There are 2 atoms of H on the left side and 6 atoms on the right side. It can be balance by writing 3 before H₂ as shown below:
Fe₂O₃ + 3H₂ —> 2Fe + 3H₂O
Now, the equation is balanced.
Thus, the coefficient of Fe₂O₃ is 1
A gas cylinder initially contains 463 L of gas at a pressure of 159 atm. If the final volume of gas is 817 L, what is the final pressure?
Answer:
The final pressure is 90.1 atm.
Explanation:
Assuming constant temperature, we can solve this problem by using Boyle's Law, which states:
P₁V₁=P₂V₂Where in this case:
P₁ = 159 atmV₁ = 463 LP₂ = ?V₂ = 817 LWe input the given data:
159 atm * 463 L = P₂ * 817 LAnd solve for P₂:
P₂ = 90.1 atmThe final pressure is 90.1 atm.
How many atoms are in 57.5 liters of xenon gas at STP
Answer:
1.55 × 10²⁴ atoms Xe
General Formulas and Concepts:
Atomic Structure
Reading a Periodic TableMolesSTP (Standard Conditions for Temperature and Pressure) = 22.4 L per mole at 1 atm, 273 K Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.Stoichiometry
Using Dimensional AnalysisExplanation:
Step 1: Define
[Given] 57.5 L Xe at STP
[Solve] atoms Xe
Step 2: Identify Conversions
[STP] 22.4 L = 1 mol
Avogadro's Number
Step 3: Convert
[DA] Set up: [tex]\displaystyle 57.5 \ L \ Xe(\frac{1 \ mol \ Xe}{22.4 \ L \ Xe})(\frac{6.022 \cdot 10^{23} \ atoms \ Xe}{1 \ mol \ Xe})[/tex][DA] Divide/Multiply [Cancel out units]: [tex]\displaystyle 1.54583 \cdot 10^{24} \ atoms \ Xe[/tex]Step 4: Check
Follow sig fig rules and round. We are given 3 sig figs.
1.54583 × 10²⁴ atoms Xe ≈ 1.55 × 10²⁴ atoms Xe
The reduction of iron(III) oxide () to pure iron during the first step of steelmaking, ()()() is driven by the high-temperature combustion of coke, a purified form of coal: ()()() Suppose at the temperature of a blast furnace the Gibbs free energies of formation of and are and , respectively. Calculate the maximum mass of pure iron that can be produced by the combustion of of coke. Round your answer to significant digits.
Answer:
hello your question is incomplete attached below is the complete question
answer : To 2 significant digits = 5500 kg
Explanation:
Given
C(s) + O2 (g) ----------> CO2 ( g )
mass of CO2 = 8.9 * 10^6 g
number of moles = 8.9 * 10^6 / 12 = 7.416 * 10 ^5 mol
same amount of moles is needed by O2 hence
attached below is the detailed solution
An analytical chemist is titrating 111.0 mL of a 0.3700 M solution of aniline (C6H5NH2) with a 0.3500 M solution of HNO3. The pK_b of aniline is 9.37. Calculate the pH of the base solution after the chemist has added 79.1 mL of the HNO_3 solution to it.
Answer:
The answer is "4.31"
Explanation:
aniline millimoles [tex]= 111 \times 0.37 = 41.07[/tex]
added [tex]HNO_3[/tex] millimoles [tex]= 79.1 \times 0.35 = 27.685[/tex]
[tex]\to 41.07 - 27.685 = 13.385[/tex] millimoles aniline left
[tex]\to 27.685[/tex] millimoles salt formed
total volume[tex]= 111 + 79.1 = 190.1\ mL\\\\[/tex]
[tex]\to [aniline] = \frac{13.385}{190.1} = 0.07 \ M\\\\\to [salt] =\frac{ 27.685}{ 190.1} = 0.146\ M\\\\\to pOH = pKb + \frac{\log [salt]}{ [base]}\\\\\to pOH = 9.37 + \frac{\log [0.146]}{[0.07]}\\\\\to pOH = 9.69\\\\\to pH = 14 - 9.69\\\\\to pH = 4.31\\[/tex]
Which letter in the rock cycle diagram represents metamorphic rock?
A)
A.
B)
B.
)
D.
D)
E.
Answer:
B.Explanation:
Hopes this helps. Mark as brainlest plz!Answer:
b
Explanation:
learned this in science class
Chrysanthemic acid occurs as a mixture of esters in flowers of the chrysanthemum (pyrethrum) family.
a. True
b. False
Answer:
A: True
Explanation:
Statement is true because chrysanthemic acid is formed naturally as a result of production of two molecules of dimethylallyl diphosphate which forms pyrophosphate ester.
Thus, it belongs to the pyrethrum family
The equation H2 + O2 -> H2O is unbalanced. When balanced, what is the correct coefficient for O2?
Answer:
The balanced equation would be 2H2 + O2 -> 2H2O
Explanation:
The correct balanced equation is 2H₂ + O₂ → 2H₂O, and the correct coefficient for O₂ is 1.
How to balance a chemical equation?Count the atoms on each side first. Next, alter one of the compounds' coefficient. Third, count the atoms once more, and then repeat steps two and three until the equation is balanced.
In the given equation, hydrogens are already balanced. To balance oxygen, multiple water with 2. Thus, equation becomes:
H₂ + O₂ → 2 H₂O
Now, oxygen is balanced, just the hydrogens got unbalanced. To balance hydrogen, multiply the hydrogen by 2 on the left side.
2 H₂ + O₂ → 2H₂O
Now the chemical equation is balanced, in which the number of oxygen and hydrogen are equal on both sides of the arrow.
Therefore, the coefficient of O₂ is 1.
Learn more about chemical equation, here:
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Question 2
1 pts
r
A compound is 31.1 % S, the rest is chlorine. The compound has a molecular mass of 205.94 amu.
What is its molecular formula?
Explanation:
its hard to explain unless we know what the question fully asks..
Describe in your own words what is an air front is
Answer:
A front is a weather system that is the boundary separating two different types of air. One type of air is usually denser than the other, with different temperatures and different levels of humidity.
What is the mass in grams of precipitate formed when 250.0 mL of 0.360 M ZnCl₂ is mixed with excess KOH in the following chemical reaction?
ZnCl₂ (aq) + 2 KOH (aq) → Zn(OH)₂ (s) + 2 KCl (aq)
Answer:
8.95 g
Explanation:
ZnCl₂ (aq) + 2 KOH (aq) → Zn(OH)₂ (s) + 2 KCl (aq)First we calculate how many ZnCl₂ moles reacted, using the given concentration and volume:
250 mL / 1000 = 0.250 L0.360 M * 0.250 L = 0.090 mol ZnCl₂Then we convert ZnCl₂ moles into Zn(OH)₂ moles [ Zn(OH)₂ is the precipitate, as it is the solid]:
0.090 mol ZnCl₂ * [tex]\frac{1molZn(OH)_2}{1molZnCl_2}[/tex] = 0.090 mol Zn(OH)₂Finally we convert 0.090 Zn(OH)₂ moles into grams, using its molar mass:
0.090 mol Zn(OH)₂ * 99.424 g/mol = 8.95 gThe mass of a substance is the product of the molar mass and the moles of the substance. The mass of precipitate formed in the reaction is 8.95 gm.
What is Mass?The mass of the substance is the weight of the compound or the molecule present in the sample.
The balanced chemical reaction is shown as:
[tex]\rm ZnCl_{2} (aq) + 2 KOH (aq) \rightarrow Zn(OH)_{2} (s) + 2 KCl (aq)[/tex]
Given,
Volume (V) of zinc chloride = 0.250 L
Molarity of zinc chloride (M) = 0.360M
Moles of zinc chloride are calculated as:
[tex]\begin{aligned} \rm moles &= \rm molarity \times volume \\\\&= 0.360 \times 0.250\\\\&= 0.090 \;\rm mol\end{aligned}[/tex]
Moles of zinc hydroxide from zinc chloride are calculated as:
[tex]0.090\;\rm mol \; ZnCl_{2} \times \dfrac{ 1\;\rm mol \;\rm Zn(OH)_{2}}{1\;\rm mol\; ZnCl_{2}} = 0.090 \;\rm mol[/tex]
Mass is calculated as:
[tex]\begin{aligned} \rm mass &= \rm moles \times molar \; mass\\\\&= 0.090 \times 99.424 \\\\&= 8.95 \;\rm gm\end{aligned}[/tex]
Therefore, 8.95 gm precipitate is formed.
Learn more about mass here:
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Your friend had an upset stomach caused by indigestion. His mother explained to him
that indigestion is when the contents in the stomach are too acidic. She also told him to
drink soda to settle his stomach. The soda did not help. You tell him that you would not
have expected the soda to help with the indigestion based on what you know about
acids and bases.
ليالي
Baking Soda
Acidic
Neutral
Basic
Explain why soda would not help settle your friend's stomach. In your reponse, be sure
to include:
• a better alternative to drinking soda.
• how each substance above would react with the stomach acid.
• defining characteristics of acids and bases, besides how they react.
Be sure to consider the completeness of your response, supporting details, and accurate
use of terms.
Answer:
because it may cause burn that causes acid to build up which causes you to keep having an upset stomach
I take in oxgyen from the air and send it into your bloodstream. I also remove the carbon dioxide from your body. What system am I?
muscular system
respiratory system
digestive system
skeletal system please help
The molecular weight (MW) of CuSO4 is 250g/mol. How many grams of CuSO4 are needed to make a 10 ml solution that has a molarity of 2.0 M?
Answer:
Explanation:
(The MW of CuSO4 is 250 g/mol).
Answer:
5 grams of CuSO4
Explanation:
First you make a stoichiometric relationship between the molarity and liters. So there is 2 mols per every liter. Then you put in the moleculur weight( for every mol there is 250 g). Then you have to get rid of the liters, so you times the equation by 0.01(this was found by 10ml converted into liters). After all of that you should end up with 5 grams of CuSo4
If 4.50 moles of C2H6 undergoes combustion, how many moles of oxygen would it combust with?
Answer:
First balance the equation
C2H6 + 7/2O2 2CO2 +3H2O
for one mole of C2H6 there are 7/2 mole of O2 required. so for4.50 moles you require 4.50 x 7/2 = 15.75 moles of O2.
Explanation:
Why does understanding the Rock Cycle help us to plan living on the ocean? answer before it's too late!
Answer:
Learning the rock cycle and understanding the processes involved helps all of us. This is how soil forms, through the breakdown of rocks. We need soil to survive—imagine trying to grow vegetables without it. This is an immediate connection to the food chain
In this project, you will develop a model of a chemical reaction that either releases energy or absorbs energy. Whether a reaction releases or absorbs energy depends on the overall difference in the bond energies of the reactants and products. Your model should show the relationships between the parts of the system. These parts are the molecules and atoms that take part in the reaction. The model should also distinguish the reaction system from other systems.
Answer:
that ain't chemistry that's science
Write a scientific explanation that answers the following question: Is matter conserved during a
chemical reaction in both closed and open systems?
Claim:
Evidence:
Reasoning:
Answer:
Matter is conserved during all chemical reactions because matter cannot be created or destroyed.
Explanation:
Give an example of a model used in Earth science. Explain why models are particularly important to this field.
Answer:
Some examples include maps and globes. Conceptual Models - These models serve as a tool to piece together a variety of concepts together so that we can better conceptualize the phenomena under investigation.
Scientific models are used to explain and predict the behaviour of real objects or systems and are used in a variety of scientific disciplines, ranging from physics and chemistry to ecology and the Earth sciences
What is an ionic solid?
Explanation:
In chemistry, an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions.
Which is a correct comparison between the modern quantum model and John Dalton’s model of the atom?
Answer:
No comparison => John Dalton did NOT postulate an atomic structure.
Explanation:
Dalton's postulates are based upon generalizations of observable phenomena. Micro structure was not proposed. The atomic structure that's accepted in the scientific community evolved from conclusions of ...
Thompson's raisen pudding model => electrons suspended in a positive matrix
Rutherford's shell model => dense positive nucleus surrounded by an electron cloud. (No fine structure postulated)
Bohr Concentric Ring Model => electrons orbiting a positive nucleus in discrete energy levels much like planets orbiting the sun.
Schrodinger - Dirac Quantum Models => electrons occupying specific orbital energy levels as based upon statistical wave mechanics.
Is it posible Count a grain of sand?explain
Answer:
Yes
Explanation:
As long as its a solid, you can count it. It will be hard, but possible.
How many moles is 30 grams of CO2?
Answer:
68
Explanation: