Answer:
pH = 4.50
Explanation:
A weak acid HX reacts with NaOH as follows:
HX + NaOH → H2O + NaX
Initial moles of HX are:
0.585L * (0.200mol / L) = 0.117 moles of HX
The moles of NaOH are moles of NaX that are produced, that means:
0.500L * (0.140mol / L) = 0.07 moles of NaOH = 0.070 moles of NaX produced.
And moles of HX that still in solution are:
0.117 moles - 0.070 moles = 0.047 moles of HX
To find the pH of this buffer (Mixture of a weak acid, HX with its conjugate base, NaX) we use H-H equation:
pH = pKa + log [NaX] / [HX]
Where pKa is -log Ka = 4.327
And [] could be taken as moles of each species.
Replacing:
pH = 4.327 + log [0.070] / [0.047]
pH = 4.50
Which of these terms describes an organism that eats green algae and shrimp?O A. a carnivore
O B. an omnivore
O C. a herbivore
O D. a detrivore
ASAP
Answer: C. a herbivore
Explanation: it's not a because omnivores eat plants and animals not Detritivores, are heterotrophs that obtain nutrients by consuming detritus
but herbivores eat vegetables and plants
i'm a herbivore i don't eat meat :)
Complete analysis question 2 from page B-63 in your book. "Was there copper in Cups 1-6? How did you know it was or was not there? Explain using evidence from this activity"
Answer:
I NEED HELP TOO AND ALSO PLEASE DONT 1 STAR 5 STAR FOR THE MEMES
Explanation:
Answer:
cup 2
Explanation:
it has more water in there therefore its more diluted
Which substance is oxidised 2MgO + O2 → 2MgO
Answer:
Here the oxidizing agent is Mg and the reducing agent is the O2.
This is because Mg is getting taking in O and is reducing itself to form MgO.
This Magnesium oxide, or magnesia, so formed is a white hygroscopic solid mineral that occurs naturally as percales and is a source of magnesium.
Explanation:
A lab group was calculating the speed of a radio car. They measured the distance traveled to be 6 meters and the time to be 3.5 seconds. Then they divided the distance by the time to find the speed. The actual speed was 2.2 m/s. What was their percent error?
Answer:456
Explanation:
An atom of argon has a radius of and the average orbital speed of the electrons in it is about . Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of argon. Write your answer as a percentage of the average speed, and round it to significant digits.
Here is the full question:
An atom of argon has a radius of 71 .pm and the average orbital speed of the electrons in it is about 3.9 × 10⁷ m/s. Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of argon. Write your answer as a percentage of the average speed, and round it to significant digits.
Answer:
Explanation:
From the above information:
The radius of an atom of argon = 71 .pm = 71 × 10⁻¹² m
The diameter of the atom of argon Δx =142 × 10⁻¹² m
According to Heisenberg's Uncertainty Principle,
[tex]\Delta x. \Delta p_x \geq \dfrac{h}{2}[/tex]
[tex]\Delta x. \Delta V \geq \dfrac{h}{4 \pi m_e}[/tex]
[tex]\Delta V \geq \dfrac{h}{4 \pi m_e \Delta_x}[/tex]
[tex]\Delta V \geq \dfrac{6.634 \times 10^{-34} \ J.s}{4 \pi \times 9.1 \times 10^{-3} \ kg \times 142 \times 10^{-12} \ m}[/tex]
[tex]\Delta V \geq \dfrac{6.634 \times 10^{-34} \ J.s}{1.62382641 \times 10^{-11} \ kg.m}[/tex]
[tex]\Delta V \geq 4.08 \times 10^5 \ m/s[/tex]
where; the average speed [tex]V_{avg}[/tex] = 3.9 10⁷ m/s
∴
The percentage of the average speed is expressed as a fraction of:
[tex]\% = \dfrac{4.08 \times 10^5}{3.9 \times 10^7}\times 100[/tex]
[tex]\% =1.0462[/tex]
[tex]V_{avg } = 1.046 \times 10^0[/tex]
[tex]\mathbf{V_{avg }\simeq 1.0 \%}[/tex]
Calculate the pH at of a solution of trimethylammonium chloride . Note that trimethylamine is a weak base with a of . Round your answer to decimal place.
Answer:
pH = 11.9
Explanation:
The solution is 0.93M. The pKb is 4.19
The general equation of a weak base, X, is:
Kb = [OH⁻] [XH⁺] / [X]
Where Kb is 10^-pKb = 6.457x10⁻⁵
[OH⁻] and [XH⁺] comes both from the same equilibrium and its concentration, X, is the same = [OH⁻] = [XH⁺] = X
And [X] could be taken as the initial concentration of the weak acid, 0.93M
Kb = [OH⁻] [XH⁺] / [X]
6.457x10⁻⁵ = X² / 0.93M
6x10⁻⁵ = X²
X = 7.749x10⁻³M = [OH⁻]
As pOH = -log[OH⁻]
pOH = 2.11
pH = 14 - pOH
pH = 11.9The world's annual ____
is currently approximately 1.2 percent, at which rate the world's population is projected to double in about 54 years.
I have an oxidation number of -3 and I have 5 energy levels. What element am I?
A. Yttrium
B. Phosphorus
C. Antimony
D. Bismuth
Antimony I think but I am not sure
The combustion of hexane is given by the following reaction. 2 C 6 H 14 + 19 O 2 → 12 CO 2 + 14 H 2 O The enthalpy of reaction is −4163.0 kJ/mol. How much energy (in joules) will be released if 72.78 grams of hexane is burned. (Molar mass of hexane = 86.20 g/mol).
Answer:
[tex]E=3.5149kJ[/tex]
Explanation:
Hello.
In this case, for such combustion of hexane which release heat, we can compute that amount by taking into account that the reaction releases 4163.0 kJ of energy every 1 mole of hexane, it means that for 72.78 g, which in moles is:
[tex]n_{hexane}=72.78g*\frac{1mol}{86.20g}=0.8443mol[/tex]
Thus the energy released when 0.8443 moles of hexane are released turn out:
[tex]E=n_{hexane}\Delta _cH=0.8443mol*-4163.0\frac{kJ}{mol}*\frac{1000J}{1kJ} \\\\E=3.5149kJ[/tex]
Best regards!
The ph of a lime is 1.90. What is the [H3O+]?
Answer:
thts the acidic presence
Explanation:
A student tries to balance the equation by changing the subscript 2 on Cl to a 3. Explain why this is not correct. What is the correct balanced equation
The question is incomplete, the complete question is;
“Consider the unbalanced chemical equation. Al(s) + Cl2(g) ------> AlCl3(s) A student tries to balance the equation by changing the subscript 2 on Cl to a 3. Explain why this is not correct. What is the correct balanced equation?”
Answer:
2Al(s) + 3Cl2(g) ------> 2AlCl3(s)
Explanation:
If the student changes the subscript of Cl from 2 to 3, he/she has written a symbol for a molecule that does not exist. Halogens exist as diatomic and not triatomic gases.
The balanced equation is; 2Al(s) + 3Cl2(g) ------> 2AlCl3(s).
Notice that the basic principles of valency are not violated in any of the species in the equation above. Cl3 violates the octet rule but Cl2 obeys the octet rule.
calculate the ph at 25 c of a .33 m solution of sodium benzoate. note that benzoic acid is a weak acid with a pka of 4.2
Answer:
The pH at 25°C of 0.33M solution is 5.36.
Explanation:
Let us calculate -:
[tex]NaC_6H_5CO_2$\rightarrow$ salt of weak acid + sodium benzoate[/tex]
pH of salt of weak acid and sodium benzoate is given by-
pH =[tex]7+\frac{1}{2}pk_a+\frac{1}{2}log (concentration of salt)[/tex]
concentration of salt = 0.33M
[tex]pK_a=4.2[/tex]
[tex]pH = 7 +\frac{4.2}{2} +\frac{1}{2}log (0.33)[/tex]
[tex]pH=7 +\frac{4.2}{2} + \frac{(-0.4815)}{2}[/tex]
pH = 5.36
Hence , the answer is 5.36
All of the following complexes will be colored (in the visible) EXCEPT ________. a) [Zn(en)3]2 b) [Fe(CN)6]4- c) [Ni(H2O)6]2 d) [Cr(NH3)6]3 e) [Cu(NH3)4]2
Answer:
a
Explanation:
All of the complexes will be colored except [Zn(en)3]2.
Fe, Ni, Cr, and Cu all form colored complexes because of their partially-filled d-orbitals and are generally referred to as transition elements. The d-orbital can split into higher and lower orbitals and electrons can jump from one level to the other. The jumping of electrons leads to light absorption and this characteristic impacts color to elements with partially-filled d-orbitals.
Zinc does not possess a partially-filled d-orbital and as such, its electrons cannot transition between levels, even though it belongs to the 'd-block' element.
The correct option is a.
Compound 1 melts at 40 degrees Celsius. Compound 2 melts at 1310 degrees Celsius. Compound 3 melts at
240 degrees Celsius. Compound 4 melts at -62 degrees Celsius. Which is most likely to be an ionic compound?
Compound 4
Compound 2
Compound 3
Compound 1
Explanation:
We know that,
Ionic compound have high melting point.Here,
Compound 2 has high melting point.
So,
Compound 2 is most likely to be an ionic compound.
A 0.25g sample of Lead-210 has a half life of 20.4 years. Will all of the Lead undergo radioactive decay in 150 years? Explain.
(I really need help on this this the last question for my assignment but i’m completely lost since i don’t think she covered how we’re supposed to solve this and explain it)
Answer:
Using the equation A(t) = 400e-.032t
a) replace t with 4 so A(4) = 400e((-.032)(4))
The hardest part about this is making sure to use order of operations. Be certain it works like this:
A(4) = 400e-.128
A(4) = 400(.8799)
A(4) = 351.9 grams
b) A(8) = 400e((-.032)(8)) = 309.7 grams
c) A(20) = 400e((-.032)(20)) = 210.9 grams
Note here that even after 20 years, not quite half of the original amount is gone. So, we can anticipate that in finding the half life, that our answer should be slightly greater than 20 years.
d) 200 = 400e(-.032t)
Divide both sides of the equation by 400.
.5 = e(-.032t)
Change this to logarithmic form.
Ln .5 = -.032t
-.6931≈ -.032t
t ≈ 21.7 years
Explanation:
Titanium has an HCP unit cell for which the ratio of the lattice parameters c/a is 1.58. If the radius of the Ti atom is 0.1445 nm, calculate the density of Ti and compare it with the literature value of 4.51 g/cm3 . The atomic mass of titanium is 47.87 g/mol.
Answer:
4.81 g / mol
Explanation:
Given :
Titanium has an HCP unit cell
Radius of titanium, R = 0.1445 nm
Unit cell volume, [tex]$V_c= 6R^2 C\sqrt3$[/tex]
But for Ti, c/a = 1.58
So, c = 1.58 a
And a = 2R or c = 3.16 R
[tex]$V_c = 6R^2 \times 3.16 R \times \sqrt3$[/tex]
[tex]$V_c=6 \times 3.16 \times \sqrt3 \times (1.445 \times 10^{-8})^3 $[/tex]
[tex]$V_c= 9.91 \times 10^{-23}\ cm^3 / unit \ cell $[/tex]
Density of Ti (theoretical), [tex]$\rho=\frac{n. A_{Ti}}{V_C.N_A} $[/tex]
For HCP, n = 6 atoms per unit cell and atomic mass = 47.87 g/mol
[tex]$\rho=\frac{6 \times 47.87}{9.91 \times 10^{-23} \times 6.023 \times 10^{23}} $[/tex]
= 4.81 g/mol
This is the theoretical density of titanium.
The value given in literature is 4.51 g/mol
g determine the mass of products formed by the combustion of 7.600 g of a compound with empirical formula c7h12
Answer:
[tex]m_{CO_2}=24.38gCO_2\\m_{H_2O}=8.550gH_2O[/tex]
Explanation:
Hello.
In this case, since the combustion of C7H12 which is probably heptyne (molar mass = 96 g/mol) is:
[tex]C_7H_1_2+10O_2\rightarrow 7CO_2+6H_2O[/tex]
In which the products are carbon dioxide (molar mass = 17 g/mol) and water (18 g/mol) that are in a 7:1 and 6:1 mole ratio with the heptyne, respectively; thus, the yielded mass of both carbon dioxide and water is:
[tex]m_{CO_2}=7.600gC_7H_{12}*\frac{1molC_7H_{12}}{96gC_7H_{12}}*\frac{7molCO_2}{1molC_7H_{12}} *\frac{44gCO_2}{1molCO_2} \\m_{CO_2}=24.38gCO_2\\\\m_{H_2O}=7.600gC_7H_{12}*\frac{1molC_7H_{12}}{96gC_7H_{12}}*\frac{6molH_2O}{1molC_7H_{12}} *\frac{18gH_2O}{1molH_2O} \\m_{H_2O}=8.550gH_2O[/tex]
Best regards.
Which may be true for a substance that absorbs energy?
ОА.
The energy decreases the molecular motion but increases the kinetic energy of the substance.
The energy increases the molecular motion and the kinetic energy of the substance.
OB.
Ос.
The energy decreases the molecular motion and the kinetic energy of the substance.
OD
The energy increases the molecular motion but decreases the kinetic energy of the substance.
Answer:
The energy increases the molecular motion and the kinetic energy of the substance.
Explanation:
A substance that absorbs energy will have their kinetic energy increased and also the molecular motion.
This is in compliance with the kinetic molecular theory of gases.
When a body gains energy, the molecules becomes more energized. They begin to vibrate about a fixed point in a lattice. This also increases the kinetic energy of the substance. Kinetic energy is the energy due to the motion of the particles of a medium.how do you Pangea and plate tectonic differ?
A silver ring has a density of 10.50 g/mL. What is the mass of the ring that has a volume of 10.0 mL?
20.5 g?
105 g?
0.952 g?
Answer:
the answer is 105 g/mL
Explanation:
beacuse mass = density×volume
What volume of 6.0 M HCl would you need to add to a 800.0 mL of 0.10 M NaAc to give a final pH = 4.30? The pKa of HAc is 4.78. Give the answer in milliliters, using 2 sig. figs.
Answer:
3.33 ml
Explanation:
We have
pH to be equal to pKa + log [ NaAc / HAc]
pH = 4.30
pKA = 4.78
This is expressed as
4.30 = 4.78 + log [ NaAc / HAc]
log [ NaAc / HAc] = - 0.48
[ NaAc / HAc] = 10^-0.48
= 0.33
Naac/HAc = 0.33
From here we cross multiply to get
NaAc = 0.33 HAc
The ratio can be given as 1 : 0.33 or 3:1
Moles of NaAc = 800 x 0.10 / 1000
= 0.08
With a ratio of 3 : 1 NaAC and HAc
We have 0.06 mol NaAc and 0.02 mol HAc
moles of HCl = 0.02 mol
Volume of Hcl = 0.02x1000 = 20
20/6.0
= 3.33 Ml
The volume of 6.0 M HCL should be 3.33 ml.
Calculation of the volume:Since
pH to be equal to pKa + log [ NaAc / HAc]
pH = 4.30
pKA = 4.78
Now we can do like
4.30 = 4.78 + log [ NaAc / HAc]
log [ NaAc / HAc] = - 0.48
[ NaAc / HAc] = 10^-0.48
= 0.33
Naac/HAc = 0.33
Now
NaAc = 0.33 HAc
The ratio can be given as 1 : 0.33 or 3:1
So,
Moles of NaAc = 800 x 0.10 / 1000
= 0.08
With a ratio of 3 : 1 NaAC and HAc
We have 0.06 mol NaAc and 0.02 mol HAc
And,
moles of HCl = 0.02 mol
So,
Volume of Hcl = 0.02x1000 = 20
= 20/6.0
= 3.33 Ml
hence, The volume of 6.0 M HCL should be 3.33 ml.
learn more about volume here: https://brainly.com/question/13679920
The density of a gas is 2.49 g/L at 3.00 atm and 25oC. Calculate the molar mass of the gas. Multiple choice question. 2.0 g/mol 20.3 g/mol 18.3 g/mol 24.9 g/mol
Answer:
Molar mass = 20.3 (Approx)
Explanation:
Given:
Density = 2.49 g/l
Pressure = 3 atm
Tempreture = 25 degree celcius = 273 + 25 = 298 k
Find:
Molar mass
Computation:
pm = drt
3(m) = (2.49)(298)(0.0821)
m = 20.3 (Approx)
Molar mass = 20.3 (Approx)
In this periodic table, which color or colors represent the elements that are
metals?
A. Blue and green
B. Orange and green
C. Orange only
D. Blue only
Answer:
D
Explanation:
the metal are on the left and in the middle
There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. Therefore, the correct option is option D that is Blue only.
What is periodic table?Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.
Periodic table help a scientist to know what are the different types of elements are present in periodic table so that they can discover the new elements that are not being discovered yet.
The elements which is colored blue are elements that are metals. Metals are mostly on the left side of the periodic table. Metals loose lectrons easily. Metals are lustrous, malleable and ductile.
Therefore, the correct option is option D that is Blue only.
Learn more about periodic table, here:
https://brainly.com/question/11155928
#SPJ2
Plants and animals that share a______ often help each other survive. Plants provide food and shelter for animals. In turn, animals help plants reproduce. When bees and other insects gather____they also carry______from flower to flower. This helps to_____the flowers. The______ of each flower then produces seeds and grows into a fruit. Other animals scatter the seeds.
Answer:
biome or habitat, nectar, pollen, pollinate, propagation
Explanation:
Do any of these terms sound familiar?
which outcome occurs as a multicellular organism develops
Answer:
A multicellular organism develops from a single cell (the zygote) into a collection of many different cell types, organized into tissues and organs. Development involves cell division, body axis formation, tissue and organ development, and cell differentiation (gaining a final cell type identity).
Explanation:
1 Sound waves, water waves, and light waves are all alike in that they all ____________.
Answer:
They all produce a type of energy
Explanation:not sure but in wat i remenber that wat i learned in 5th grade
what is equal to a temperature of 20 celsius
Answer:
68 degrees fahrenheit or 293.15 degrees kelvin
Explanation:
Answer:
68°F
Explanation:
Identify the nucleic acid DNA
1. Cholesterol
2. Proteins
3. Disacharide
Answer:
DNA
Explanation:
A 293.9 mL sample of a 0.275 M solution is left on a hot plate overnight; the following morning the solution is 1.10 M. What volume of solvent in mL has evaporated from the 0.275 M solution
Answer:
220.4mL were evaporated
Explanation:
First, we are going to calculate the moles of the solution. Then, with the new concentration we can solve the volume of the solution and the evaporated volume:
Moles initial solution:
293.9mL = 0.2939L * (0.275mol / L) = 0.08082 moles of solution.
As the new concentration is 1.10M, the new volume must be:
0.08082 moles of solution * (1L / 1.10mol) = 0.07348L =
73.5mL you have still present in you solution
And evaporated volume is:
293.9mL - 73.5mL =
220.4mL were evaporatedA sample of element Z, which has two isotopes, is made up of 75% Z-12 and 25% Z-13. Calculate the average atomic mass. Round your answer to TWO PLACES after the decimal. Enter your answer as a number (no units)
Answer:
Average atomic mass = 12.25
Explanation:
Percent abundance of Z-12 = 75%
percent abundance of Z-13 = 25%
Average atomic mass = ?
Solution:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) / 100
Average atomic mass = (75×12)+(25×13) /100
Average atomic mass = 900 + 325 / 100
Average atomic mass = 1225 / 100
Average atomic mass = 12.25 amu.