Answer:
we don't understand why humans have only 46 chromosomes
Answer:
46 chromosomes is what we don't understand
g When 2.50 g of methane (CH4) burns in oxygen, 125 kJ of heat is produced. What is the enthalpy of combustion (in kJ) per mole of methane under these conditions
Answer:
-800 kJ/mol
Explanation:
To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).
First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:
Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol
moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄
Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:
ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol
Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).
Give four examples illustrating each of the following terms. a. homogeneous mixture b. heterogeneous mixture c. compound e. physical change d. element f. chemical change
1. homogenous: sugar solution
2. heterogeneous: sand solution
3. compound: water
4. physical change: ice melting
5. element: hydrogen
6. chemical change: burning fire
An antacid tablet weighing 1.30g was fully neutralized at 42.00 mL(an excess amount) of 0.250MHCl. 10.00 mL of 0.100 M NaOH was then used to back titrate the excess HCl. How many moles of acid did the antacid neutralize
Answer:
0.0095 moles of acid were neutralized by the antiacid
Explanation:
The antiacid is a base that neutralize the acid in stomach. To find the moles of acid neutralized we need to find the moles of acid added initially. This acid is added in excess, then, the moles of NaOH added reacts to neutralize the moles of acid in excess. The difference between initial moles of HCl and moles of NaOH needed to titrate the excess = Moles of HCl that were neturalized by the antiacid as follows:
Moles HCl added:
42.00mL = 0.04200L * (0.250mol/L) = 0.0105 moles HCl
Moles NaOH to titrate the excess:
10.00mL = 0.01000L * (0.10mol/L) = 0.0010 moles NaOH = Moles HCl in excess.
Moles of acid that were neutralized:
0.0105 moles - 0.0010 moles =
0.0095 moles of acid were neutralized by the antiacidWhy U.S. genetically modified ingredients ruin the taste
Answer:
I hope this helps!
Explanation:
The biggest threat caused by GM foods is that they can have harmful effects on the human body. It is believed that consumption of these genetically engineered foods can cause the development of diseases which are immune to antibiotics. ... As the health effects are unknown, many people prefer to stay away from these foods.
Calculating the expected pH of the buffer solution: Given that the pKa for Acetic Acid is 4.77, calculate the expected pH of the buffer solutions using the Henderson-Hasselbalch equation and the concentrations of Acetic Acid and Acetate added to the 250 ml Erlenmeyer flask: pH
Answer:
[tex]pH=4.77[/tex]
Explanation:
From the question we are told that:
pKa for Acetic Acid [tex]pK_a= 4.77[/tex]
Therefore
For Equal Concentration of acetic acid and acetatic ion
[tex]CH_3COOH=CH_3COO^-[/tex]
Generally the Henderson's equation for pH value is mathematically given by
[tex]pH=pK_a+log\frac{base}{acid}[/tex]
[tex]pH=4.77+log\frac{CH_3COO^-}{CH_3COOH}[/tex]
[tex]pH=4.77+log1[/tex]
[tex]pH=4.77[/tex]
What volume of each solution contains 0.14 mol of KCl? Express your answer using two significant figures.
1.8 M KCl
Answer:
Solution given:
1 mole of KCl[tex]\rightarrow [/tex]22.4l
1 mole of KCl[tex]\rightarrow [/tex]74.55g
we have
0.14 mole of KCl[tex]\rightarrow [/tex]74.55*0.14=10.347g
74.55g of KCl[tex]\rightarrow [/tex]22.4l
10.347 g of KCl[tex]\rightarrow [/tex]22.4/74.55*10.347=3.11litre
volume of each solution contains 0.14 mol of KCl contain 3.11litre.
1 mol of any gas contains 22.4L of volume at STP
Moles of KCl=0.14Volume of KCl:-
0.14(22.4)3.14LSelect the choice that best completes the following sentence: When cooled slowly, transformations near the melting temperature tend to yield ______ grains due to the formation of ______ nucleation sites followed by ______ grain growth.
Question Completion with Options:
O coarse...few...rapid
O fine...few...slow
O fine...multiple...rapid
O coarse...few...slow
O fine...multiple...slow
Answer:
The choice that best completes the sentence is:
O coarse...few...slow
Explanation:
Transformations near the melting temperature develop coarse grains because few nucleation sites are formed and the rate of the grain growth is usually slow. This is because of the process that starts with recrystallization, recovery, and nucleation before growth can occur. While recrystallization enables the grain to increase in size at high temperature, nucleation gives the grain the energy to irreversibly grow into larger-sized nucleus.
what is the mass of 4 moles of fluorine atoms?
Answer:
Vien, sometimes we make problems like this harder than they need to be. Suppose I asked you, “How many dozen wheels are on four dozen automobiles?” You would have no trouble answering 4 x 4 = 16 dozen.
A mole is just a quantity like a dozen. And in this case, instead of 4 wheels, each C2F6 molecule bears 6 fluorine atoms, right?
So 4 x 6 = 24 moles of fluorine atoms. You’ve got this, Vien!
Predict whether solutions of each of the following salts will be acidic, basic, or neutral. Explain your reasoning for each by writing a balanced net ionic equation to describe the chemistry of each non-neutral salt in water:
a. NaCN
b. KNO3
c. NH4Cl
d. NaHCO3
e. Na3PO4.
Answer:
NaCN- basic salt
KNO3 - neutral salt
NH4Cl - acid salt
NaHCO3 - acid salt
Na3PO4 - acid salt
Explanation:
Salt hydrolysis a process by which salts react with water giving an acid and a base.
When we dissolve NaCN in water, we have;
NaCN + - ⇄ Na^+ + CN^-
KNO3 ------> K^+ + NO3^-
NH4Cl ------> NH4^+ + Cl^-
NaHCO3 -----> Na^+ + HCO3^-
Na3PO4 ----> 3Na^+ + PO4^3-
Note that if a salt is formed from a weak acid and a strong base, the salt will be a basic salt e.g NaCN formed from weak HCN and strong NaOH.
If a salt is formed from a strong acid and weak base, the salt will be acidic, e.gNH4Cl formed from weak NH3 and strong HCl.
If a salt is formed from a strong acid and strong base, the salt will be neutral, e.g KNO3 formed from strong KOH and strong HNO3.
When a 1:1 mixture of ethyl propanoate and ethyl butanoate is treated with sodium ethoxide, four Claisen condensation products are possible. Draw the structure(s) of the product(s) that have an ethyl group on the chiral center
Answer:
attached below
Explanation:
The Four Claisen condensation are grouped into :
Self Claisen condensation reaction Cross Claisen condensation reactionSelf Claisen condensation is when R = R'
Cross Claisen condensation is when R ≠ R'
attached below are the four Claisen condensation
Manganese-55 has _____neutrons.
55 Mn
25
A. 55
B. 30
C. 25
QUESTION:- Manganese-55 has _____neutrons.
OPTIONS :-
A. 55
B. 30
C. 25
ANSWER:- NUMBER OF NEUTRONS IS EQUAL TO THE DIFFERENCE BETWEEN THE MASS IF THE ATOM AND ATOMIC NUMBER
SO DIFFERENCE IS EQUAL TO :- 55-25 = 30 NEUTRONS.
SO THERE IS 30 NEUTRONS IN SINGLE ATOM OF THE MANGANESE-55 ATOM.
Answer:
the mass of an atom is the sum of proton and neutron which are both concentrated in nocleus of an atom. from the question the mass is given as 55 and the proton is 25.
What is Bose Einstein state of matter and their examples
Answer:
A BEC ( Bose - Einstein condensate ) is a state of matter of a dilute gas of bosons cooled to temperatures very close to absolute zero is called BEC.
Examples - Superconductors and superfluids are the two examples of BEC.
Explanation:
The electronic arrangement of an atom shows how electrons are distributed across the different energy levels. Which of the following elements is represented by the electron arrangement 2, 8, 18, 6?
А Сa
B. Mg
C. S
D Se
E. Ga
Answer:
The answer is D which is Selenium
công thức của định lý pytago
The sum of the squares of two sides of a right angle is equal to the square of the hypotenuse
20. An oxide of osmium (symbol Os) is a pale yellow solid. If 2.89 g of the compound contains 2.16 g of osmium, what is its empirical formula?
The empirical formula is OsO₄ :
Explanation:
Osmium oxide contains osmium and oxygen only.
Thus, we shall determine the mass of oxygen in osmium oxide. This can be obtained as follow:
Mass of compound = 2.89 g
Mass of Os = 2.16 g
Mass of O =?Mass of O = (Mass of compound) – (Mass of Os)
Mass of O = 2.89 – 2.16
Mass of O = 0.73 g
Finally, we shall determine the empirical formula of the compound. This can be obtained as follow:
Mass of Os = 2.16 g
Mass of O = 0.73 g
Empirical formula =..?Os = 2.16 g
O = 0.73 g
Divide by their molar mass of
Os = 2.16 / 190 = 0.011
O = 0.73 / 16 = 0.046
Divide by the smallest
Os = 0.011 / 0.011 = 1
O = 0.046 / 0.011 = 4
Empirical formula = OsO₄Learn more: https://brainly.com/question/23629778
5 points ) Which of the following is a benefit of using email to communicate at work ? a) You can express yourself in a limited number of characters b) You don't have to worry about using proper grammar. c) You always get a response right away. d ) You can reach a large audience with one communication .
Answer:
C
Explanation:
3. (07.05 LC)
When zinc reacts with hydrochloric acid, it produces hydrogen gas. As the reaction proceeds, why does the rate of production of hydrogen gas decrease? (3 points)
the rate would decrease because the reactants are being depleted.
For the following acids of varying concentrations, which are titrated with 0.50 M NaOH, rank the acids in order of least to most volume of base needed to completely neutralize the acid.
a. 0.2M H2C6H5O7
b. 0.2M H2C2O4
Answer:
0.2M H2C6H5O7 < 0.2M H2C2O4
Explanation:
A weak acid/base ionizes to a very small extent in water. Hence, if we say that a substance is a weak acid/base, its percentage of ionization in solution is very little.
More volume of a very weak acid is required to neutralize a strong base. Since NaOH is a strong base, the weaker acid among the duo will require more volume for neutralization.
Since H2C6H5O7 is a weaker acid than H2C2O4, equal concentration of the both acids will require less volume of H2C2O4 than H2C6H5O7 to neutralize 0.50 M NaOH.
H₂C₆H₅O₇ is a weaker acid than H₂C₂O₄, and will require the least volume of 0.50 M NaOH to be neutralized.
H₂C₆H₅O₇ < H₂C₂O₄
The strength of an acid is related to the value of its dissociation constant, Ka or its pKa (negative logarithm of Ka)
Strong acids have high Ka values or low pKa value, whereas weak acids have low Ka values and high pKa values.
Between two acids, the acid with a higher Ka or lower pKa values is the stronger acid.
Acids are classified as either strong or weak depending on how well it ionizes in solution to produce hydrogen ions.
Strong acids ionizes completely to produce hydrogen ions.
Weak acid ionizes partially to a varying degrees in water to produce hydrogen ions.
In neutralization reactions between acids and bases, stronger acids will require the most volume of base or alkali in order to be neutralized.
H₂C₂O₄ has a Ka value of 5.9 x 10⁻² and a pKa value of 1.23
H₂C₆H₅O₇ has a Ka value of 8.4 x 10⁻⁴ and a pKa value of 3.08
Hence H₂C₂O₄ is a stronger acid than H₂C₆H₅O₇
For equal molar concentrations of the two acids, H₂C₂O₄ will produce more hydrogen ions than H₂C₆H₅O₇, and thus, will require more volume base (0.50 M NaOH) to be neutralized.
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Kamal was told by his mother to pour water through a thin cloth into another container to further purify the water.
a) What do you think will happen to the mud and sand when pouring the water? b)Do you think the water filtered by Kamal is safe to drink?
a].When sand is added to water it either hangs in the water or forms a layer at the bottom of the container. Sand therefore does not dissolve in water and is insoluble. It is easy to separate sand and water by filtering the mixture.
b]. The water filtered by kamal is not safe to drink .
If you run out of water, or cannot carry enough water with you for your entire trip, you may need to source drinking water from natural water sources.
You are inside a room with a temperature of 11°C. You step outside and the temperature is 100°C. What is the AT?
A) 0.76°C
B) 157°C
C) 89°C
D) 6052°C
E) 1.31°C
F) 21°C
Answer:
89°c
Explanation:
i think this is the answer cause the temperature changed from 11 to 100 and so the atmospheric temperature would be the change in temperature
100-11=89°c
I hope this helps and sorry if it's wrong
lution: What is the molarity of 245 g of H, SO4 dissolved in 1.00 L of solution?
[tex]\\ \large\sf\longmapsto H_2SO_4[/tex]
[tex]\\ \large\sf\longmapsto 2(1u)+32u+4(16u)[/tex]
[tex]\\ \large\sf\longmapsto 2u+32u+64u[/tex]
[tex]\\ \large\sf\longmapsto 98u[/tex]
[tex]\\ \large\sf\longmapsto 98g/mol[/tex]
Given mass=245g[tex]\boxed{\sf No\:of\:moles=\dfrac{Given\:mass}{Molar\:Mass}}[/tex]
[tex]\\ \large\sf\longmapsto No\:of\:moles=\dfrac{245}{98}[/tex]
[tex]\\ \large\sf\longmapsto No\:of\:moles=2.5mol[/tex]
Now
[tex]\boxed{\sf Molarity=\dfrac{Moles\:of\:solute}{Volume\:of\:solution\;in\;L}}[/tex]
[tex]\\ \large\sf\longmapsto Molarity=\dfrac{2.5}{1}[/tex]
[tex]\\ \large\sf\longmapsto Molarity=2.5M[/tex]
Assume you have 4 solids (A, B, C and D) of similar mass. Which of these requires the greatest energy input to melt?
polar covalent
covalent network
ionic compound
nonpolar covalent
The solid that require the greatest energy input to melt by mass is the option;
Covalent network
Reason for the above answer is as follows;
The elementary particles of a solid are held together by bonds that require
an input of energy to unlock, and once broken, the particles are then able
to change location within their containing vessels with less restrictions
Types of bonds
Polar covalent molecular solids have the following characteristics;a) Soluble in water b) Low melting point, b) Conduct electricity
Solids that are made up of a covalent network have the following characteristicsa) High melting point temperature b) Non conductive of electricity c) Not soluble in water
Solids of ionic compounds have the following characteristics;a) High melting point temperature b) The liquid state and solution
conducts electricity c) Soluble in water
Solids that have nonpolar covalent bonds have;a) Low melting point b) Normally in the gaseous or liquid state b) Not water soluble
Therefore, the covalent network, and the solids ionic compounds require the most energy to melt, however, the strength of the ionic bond in an ionic compound is a factor the charges present and the sizes of the atom, while
the covalent network solid, are combined to form essentially as a single
molecule and therefore require the greatest heat energy input break the bonds of the molecule down in order to melt
Learn more about the properties of the different types of bonds here;
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A chemist is preparing to carry out a reaction that requires 5.75 moles of hydrogen gas. The chemist pumps the hydrogen into a 10.5 L rigid steel container at 20.0 °C. To what pressure, in kPa, must the hydrogen be compressed? (Show all work for full credit and circle your final answer) *
Answer:
The hydrogen must be compressed to 1333.13302 kPa.
Explanation:
An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of the gases:
P * V = n * R * T
In this case:
P= ?V= 10.5 Ln= 5.75 molesR= 0.082 [tex]\frac{atm*L}{mol*K}[/tex]T= 20 C= 293 K (being 0 C= 273 K)Replacing:
P* 10.5 L= 5.75 moles* 0.082 [tex]\frac{atm*L}{mol*K}[/tex] * 293 K
Solving:
[tex]P=\frac{5.75 moles* 0.082 \frac{atm*L}{mol*K} * 293 K}{10.5 L}[/tex]
P= 13.157 atm
If 1 atm is equal to 101.325 kPa, then 13.157 atm is equal to 1333.13302 kPa.
The hydrogen must be compressed to 1333.13302 kPa.
Give the IUPAC and common name
Answer:
IUPAC Name:
N-ethyl-N-methylaniline
Common Name:
Benzenamine
Un sistema formado por una única sustancia, ¿será siempre homogéneo? ¿Porqué? Piensa a partir de las definiciones y trata de corroborar o negar usando ejemplos concretos.
Una sustancia homogénea es una sustancia que se compone de una sola fase.
Recordemos que definimos una fase en química como "cantidad química y físicamente uniforme u homogénea de materia que se puede separar mecánicamente de una mezcla no homogénea y que puede consistir en una sola sustancia o una mezcla de sustancias" según Ecyclopedia Britiannica.
El hecho de que un sistema esté compuesto por una sola sustancia no lo hace es autóctono. A veces, un sistema puede estar compuesto por partículas sólidas de una sustancia en equilibrio con su líquido. El sistema contiene solo una sustancia pero en diferentes fases, por lo tanto, el sistema contiene una sustancia pero no es homogéneo.
Por tanto, el hecho de que un sistema contenga una sola sustancia no significa necesariamente que sea homogéneo.
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most naturally occurring oxygen is
Balance the following equations and write the corresponding ionic and net ionic equations (if appropriate):
a. CH3COOH(aq) + KOH(aq) →
b. H2CO3(aq) + NaOH(aq) →
c. HNO3(aq) + Ba(OH)2(aq) →
Explanation:
here are your dissolutions
To calculate the atoms of an element in a given molecule, we need to multiply stoichiometry by the number that is written on the foot of that element. Therefore, the balanced equation are
CH[tex]_3[/tex]COOH + KOH [tex]\rightarrow[/tex]CH[tex]_3[/tex]COOK + H[tex]_2[/tex]O
H[tex]_2[/tex]CO[tex]_3[/tex] (aq) + 2 NaOH(aq) [tex]\rightarrow[/tex]Na[tex]_2[/tex]CO[tex]_3[/tex](aq) + 2 H[tex]_2[/tex]O
HNO[tex]_3[/tex] + Ba(OH)[tex]_2[/tex][tex]\rightarrow[/tex]Ba(NO[tex]_3[/tex])[tex]_2[/tex]+ H[tex]_2[/tex]O
What is Balanced equation?Balanced equation is the one in which the total number of atoms of a species on reactant side is equal to the total number of atoms on product side. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, displacement reaction.
The other characteristic of balanced reaction is that physical state should be written with each compound or molecule on reactant and product side. Physical state should be written in brackets. s means solid, l means liquid, g means gas.
The balanced equation can be written as
CH[tex]_3[/tex]COOH + KOH [tex]\rightarrow[/tex]CH[tex]_3[/tex]COOK + H[tex]_2[/tex]O
H[tex]_2[/tex]CO[tex]_3[/tex] (aq) + 2 NaOH(aq) [tex]\rightarrow[/tex]Na[tex]_2[/tex]CO[tex]_3[/tex](aq) + 2 H[tex]_2[/tex]O
HNO[tex]_3[/tex] + Ba(OH)[tex]_2[/tex][tex]\rightarrow[/tex]Ba(NO[tex]_3[/tex])[tex]_2[/tex]+ H[tex]_2[/tex]O
Therefore, the balanced equation are
CH[tex]_3[/tex]COOH + KOH [tex]\rightarrow[/tex]CH[tex]_3[/tex]COOK + H[tex]_2[/tex]O
H[tex]_2[/tex]CO[tex]_3[/tex] (aq) + 2 NaOH(aq) [tex]\rightarrow[/tex]Na[tex]_2[/tex]CO[tex]_3[/tex](aq) + 2 H[tex]_2[/tex]O
HNO[tex]_3[/tex] + Ba(OH)[tex]_2[/tex][tex]\rightarrow[/tex]Ba(NO[tex]_3[/tex])[tex]_2[/tex]+ H[tex]_2[/tex]O
Learn more about the balanced equation, here:
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(URGENT FOR BRAINLIEST!!)
The diagram below shows the movement of Earth plates.
The picture shows two Earth plates one beside the other. The plate on the left is shown moving towards the right and the plate
Which of these features is most likely formed as a result of the movement of Earth plates shown in the diagram? (2 points)
a canyon
a fault
a mountain
a ridge
Answer:
mountain
Explanation:
when plates move towards each other they create mountains
#19.
An unknown sample weighs 45.2 g and takes 58.2 kJ to vaporize. What is
its heat of vaporization?
When determining the amount of oxidant present by titration, you can use iodine/starch as an indicator. First, the oxidant, like hypochlorite, oxidizes Choose... When starch and iodine are both present, the solution is Choose... During the titration, a titrant like thiosulfate reduces the
The question is incomplete, the complete question is;
When determining the amount of an oxidant present by titration, you can use iodine and starch as an indicator.
First, the oxidant, like hypochlorite, oxidizes
Choose...
neutral iodine into iodide ion
iodide ion into neutral iodine
iodate polyatomic ion into iodide ion
When starch and iodine are both present, the solution is
Choose...
blue-black
brownish yellow
clear
During the titration, the titrant, like thiosulfate, reduces the
Choose...
iodide ion into iodate polyatomic ion
neutral iodine into iodide ion
iodide ion into neutral iodine
When the iodine has completely reacted at the endpoint of the titration, the solution should become
Choose...
clear
blue-black
brownish yellow
Answer:
1. iodide ion into neutral iodine
2. blue-black
3. neutral iodine into iodide ion
4. clear
Explanation:
Hypochlorite oxidizes the iodide ion to iodine molecule according to the reaction equation;
ClO-(aq) + 2H+(aq) + 2I-(aq) ---------> 6 I2(l) + Cl- (aq)+ H2O(l)
When iodine is added, the colour of the starch solution immediately changes to blue-black.
A reduction reaction occurs when the titrant, thiosulfate is added as follows;
I2 + 2S2O32- → 2I- + S4O62-
The solution at end point is found to become clear again.
