If two half lives have passed since a scientist collected a 1.00- gram sample of a U-235, how much U-235 is left now?
answers for most finals chem test questions (10th)
Answer:
one quarter of the original amount, so 0.25 g
Explanation:
Answer:
C
Explanation:
What is the pOH of
a
2.6 x 10-6 M H+ solution?
Answer:
pH = -log 2.6 x 10-6 M
pH = 5.585
pOH= 14 - 5.585 = 8.415
8.4 as 2 sig figs
What is the pressure of gas at 496 Liters and 200 Kelvin if the original pressure was 0.250 atm. at 300 liters and 400 kelvin?
Answer:
0.076 atm
Explanation:
Using the combined gas law formula;
P1V1/T1 = P2V2/T2
Where;
P1 = initial pressure (atm)
P2 = final pressure (atm)
T1 = initial temperature (K)
T2 = final temperature (K)
V1 = initial volume (L)
V2 = final volume (L)
According to the information provided in this question;
P2 = ?
P1 = 0.250 atm
V2 = 496 L
V1 = 300 L
T2 = 200K
T1 = 400K
Using P1V1/T1 = P2V2/T2
0.250 × 300/400 = P2 × 496/200
75/400 = 496 P2/200
0.1875 = 2.48P2
P2 = 0.1875 ÷ 2.48
P2 = 0.076 atm
Question is in picture! Due in 30 minutes!
Answer:
wheresthepicture.-
Explanation:
Answer:
don't see a picture
Explanation:
Alex cut a pizza into 8 equal slices. He removed 2 of the slices of pizza. What is the measure of the angle made by the missing
Answer: 90 degrees.
Explanation:
How many moles is 17.6 g NaOH?
a
0.567 mol NaOH
b 227 mol NaOH
C
0.704 mol NaOH
d 0.440 mol NaOH
Answer:
[tex]\boxed {\boxed {\sf D. 0.440 \ mol \ NaOH}}[/tex]
Explanation:
To convert from moles to grams, the molar mass is used (mass of 1 mole). The values are the same as the atomic masses on the Periodic Table, but the units are grams per mole (g/mol) instead of atomic mass units.
1. Molar MassWe are given the compound sodium hydroxide (NaOH) and we need to look up the molar masses of the individual elements.
Na: 22.9897693 g/mol O: 15.999 g/molH: 1.008 g/molThe formula for the compound has no subscripts, so there is 1 mole of each element in 1 mole of the substance. We can simply add the molar masses.
NaOH: 22.9897693 + 15.999 + 1.008 = 39.9967693 g/molThis means there are 39.9967693 grams of sodium hydroxide in 1 mole.
2. Convert Grams to MolesUse the molar mass we found as a ratio.
[tex]\frac {39.9967693 \ g \ NaOH}{ 1 \ mol \ NaOH}[/tex]
Since we are converting 17.6 grams of NaOH to moles, we multiply by this value.
[tex]17.6 \ g\ NaOH *\frac {39.9967693 \ g \ NaOH}{ 1 \ mol \ NaOH}[/tex]
Flip the ratio so the units of grams of NaOH cancel.
[tex]17.6 \ g\ NaOH *\frac {1 \ mol \ NaOH}{ 39.9967693 \ g \ NaOH}[/tex]
[tex]17.6 *\frac {1 \ mol \ NaOH}{ 39.9967693}[/tex]
[tex]\frac{17.6 }{ 39.9967693} \ mol \ NaOH[/tex]
[tex]0.4400355406 \ mol \ NaOH[/tex]
3. RoundThe original measurement of grams has 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place.
0.4400355406The 0 in the ten thousandths place (in bold above) tells us to leave the 0 in the thousandth place.
[tex]0.440 \ mol \ NaOH[/tex]
17.6 grams of sodium hydroxide are equal to 0.440 moles of sodium hydroxide.
El modelo atómico postulado por Shrodinger refiere la corteza atómica como una nube electrónica. Verdadero. Falso.
Answer:
Falso.
Explanation:
El modelo cuántico (no relativista) de Schrodinger, piensa a los electrones como ondas estacionarias, tal que la amplitud de dichas ondas decae muy rápidamente cuando se "alejaban" del radio atómico. (Es decir, habia poca probabilidad de que los electrones escaparan del radio atomico, y era por ello que se quedaban orbitando cerca del nucleo). Es decir, podríamos pensar en esto como una "nube de probabilidades" más que una nube electronica
La idea de nube electrónica realmente viene de modelos previos, como el de Rutherford o el de Bhor, los cuales eran modelos clásicos.
You can prepare a buffer solution by combining equal moles of which pair of substances?
A. weak acid and its conjugate base
B. strong acid and a strong base
C. strong base and its conjugate acid
D. salt and a weak acid
Answer:
A. weak acid and its conjugate base
Explanation:
A buffer solution can be made with a weak acid and conjugate base or a weak base and conjugate acid.
This may help you:
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Acids_and_Bases/Buffers/Introduction_to_Buffers
Please help, lots of points!
If you were working for a beverage company, which molarity would you recommend, and what directions for mixing would you create for the drink package? Support your claims using the data you collected.
The 1.0 M beverage solution which is mixed by stirring would be the best molarity based on the data collected.
What is a beverage?A beverage is a liquid other than water which is consumed by humans to provide the body with energy and nutrients as well as to quench thirst.
A good quality beverage is sweet, fluid and clear.
From the data in the table, the molarity that meets these criteria is 1.0 M with stirring.
Therefore, I would recommend the 1.0 M beverage solution which is mixed by stirring.
Learn more about beverages at: https://brainly.com/question/27739677
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Which of the following lists describes characteristics of an acid?
Answer: Acids have a sour taste. Lemons, vinegar, and sour candies all contain acids. Acids change the color of certain acid-base indicators. Two common indicators are litmus and phenolphthalein. This are som Characteristics of acid.
Answer:
Sour tasteCorrosive (burn your skin and break down other materials)Increase the concentration of H+ when added to waterDissolve metalsDonate a hydrogen ionlow pHExplanation:
these are the characteristics of an acid.
hope this helps!
The picture below shows brown bears by the side of a river.
In this environment, the brown bears by the river are
Answer:
being peaceful
and washing up
Which of the following isotopes have 8 neutrons in the nucleus?
O-15
O-17
C-13
C-14
Answer:
C-14 have 8 neutrons in the nucleus.
Carbon atoms with 8 neutrons have an atomic mass of 14 (6 protons + 8 neutrons = 14), so this isotope of carbon is named carbon-14.
hope it helps :)
Explanation:
Answer:
its d
Explanation:
edge 21
Answer is C
Zeke is attempting to react a piece of magnesium metal with sulfuric acid. The sulfuric acid is a 5M solution. What could Zeke do
to slow down the rate at which the magnesium will react with the acid?
A)
increase the temperature
B)
add a 10M sulfuric acid solution
9)
add water to the acid to decrease its molarity
D)
add more of the 5M sulfuric acid to the reaction
Answer:
c)
Explanation:
add water to the acid to decrease its molarity
Base A dissociates 25% in water. Base B dissociates 50%. Base C dissociates
75%. Which base is the WEAKEST conductor of electricity?
Answer:Base A is the weakest conductor electricity
Explanation:
Dissociation is a factor that affects electrical conductivity. The greater the percentage of dissociation for bases the stronger the conductivity of electricity.
Given that
Base A dissociates 25% in water
Base B dissociates 50%.
Base C dissociates 75%
We can conclude that Base A is the weakest conductor oelectricity since it has the lowest percentage of dissociation.
You will be marked as brainlest if you are able to solve this question
Answer:
See Explanation
Explanation:
1) According to the question, the reactivity of a metal is measured by the temperature of the solution after reaction. The higher the temperature of the solution, the greater the reactivity of the metal. Based on this criterion, the metals can be arranged in an order of reactivity as follows;
Mg> Zn > Fe.
2) The equation of the reaction is;
Mg(s) + 2H^+(aq) ------>Mg^2+(aq) + H2(g)
If we consider the changes in oxidation number from left to right;
The oxidation number of Mg changed from zero to +2
The oxidation number of H changed from +1 to zero
Recall that a redox reaction is a reaction in which the oxidation number of species changes from left to right in the reaction. Hence this reaction is a redox reaction.
The reducing agent experiences an increase in oxidation number. In this case, Mg is the reducing agent.
The oxidation half equation is;
Mg(s) ------> Mg^2+(aq) + 2e
The reduction half equation is;
2H^+(aq) + 2e ------> H2(g)
A gas has a volume of 300 mL in a rigid container at 50oC and 1.75 atm. What will be its pressure at 100K?
Answer:
Its pressure will be 0.54 atm at 100 K.
Explanation:
Gay-Lussac's law indicates that, as long as the volume of the container containing the gas is constant, as the temperature increases, the gas molecules move faster. Then the number of collisions with the walls increases, that is, the pressure increases. That is, the pressure of the gas is directly proportional to its temperature.
Gay-Lussac's law can be expressed mathematically as the quotient between pressure and temperature equal to a constant:
[tex]\frac{P}{T} =k[/tex]
Studying two different states, an initial state 1 and a final state 2, it is satisfied:
[tex]\frac{P1}{T1} =\frac{P2}{T2}[/tex]
In this case:
P1= 1.75 atmT1= 50 °C= 323 K (being 0 C=273 K)P2= ?T2= 100 KReplacing:
[tex]\frac{1.75 atm}{323 K} =\frac{P2}{100 K}[/tex]
Solving:
[tex]P2= 100 k*\frac{1.75 atm}{323 K}[/tex]
P2= 0.54 atm
Its pressure will be 0.54 atm at 100 K.
Which reaction demonstrates bonds breaking?
PC13(g) → P (g) + 3Cl (g)
P(g) + 3 Cl(g)
PC13 (g)
Definition: This is the energy that comes to Earth from the Sun.
Example: using the sun to dry your laundry hanging on the clothesline
Answer:
well to me it is called natural energy
A gas diffuses 1/6 times faster than hydrogen gas (H2).
What is the molar mass of the gas? (5 points)
a
59.95 g/mol
b
66.54 g/mol
c
68.68 g/mol
d
72.58 g/mol
Answer:
72.58 g/mol
Explanation:
mark me brainless if I am ✅
The relationship between the rate of diffusion and the molar mass is given by Graham's law. A gas diffusing 1/6 times faster than hydrogen will have a molar mass of 72.58 g/mol. Thus, option d is correct.
What is Graham's law?Graham's law states the inverse relationship between the rate of diffusion and the square root of the molar mass of the gas. It is given as,
Rate = 1 ÷ √M
The molar mass of the gas that diffuses 1/6 times faster than hydrogen is calculated as,
R₁ ÷ R₂ = √ (M₂ ÷ M₁)
Here,
The molar mass of hydrogen = M₁
The molar mass of unknown gas = M₂
Rate of diffusion of hydrogen gas = R₁
Rate of diffusion of unknown gas = R₂ = 1 / 6 R₁
Substituting values:
R₁ ÷ 1/6 R₁ = √M₂ ÷ 2
6 × 1.414
= 8.485
= 84.85 g/mol ≈ 72.58 g/mol
Therefore, option d. 72.58 g/mol is the molar mass of unkown gas.
Learn more about Graham's law here:
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What is the chemical name for CaCl2?
Calcium chlorine
O Calcium(I) chloride
O Calcium chloride
O Calcium(II) chloride
What does all matter have in common?
A.
It is made up of atoms.
B.
It is made up of molecules.
C.
It is all solid.
D.
It is too small to see.
PLEASE HELP NEED ANSWER ASAP!!!!
Use 3 H2(g) + N2(g) <--> 2 NH3 (g) + 92.4 kJ
At equilibrium, if the hydrogen (H2) concentration is increased, the ammonia(NH3) concentration will
Select one:
a. decrease
b. shifts back and forth
c. increase
d. remain the same
Answer:
the correct answer is option A. decrease
Balance the chemical equation using the drop-down options.
CaC2 +
A H20 --->
Ca(OH)2
A C2H2 +
Answer:
CaC2 + 2H20 ⇋Ca(OH)2 + C2H2
Explanation:
CaC2 + A H20 ---> Ca(OH)2 + A C2H2
This is calcium carbide reacting with water to produce calcium hydroxide and ethyne commonly called acetylene.
Let's now balance the equation.
CaC2 + 2H20 ⇋Ca(OH)2 + C2H2
Prokaryotic and eukaryotic cells have many different characteristics. One difference
between prokaryotic and eukaryotic cells is that all eukaryotic cells —
Answer:
Have a nucleus
Explanation:
Pls check..
Please help me ASAP!!!!
Answer:
Explanation:
Determine the balanced chemical equation for the chemical reaction.
Convert all given information into moles (most likely, through the use of molar mass as a conversion factor).
Calculate the mole ratio from the given information.
Answer the following questions when 45mL sample of 0.175 M KOH is titrated with 0.200 M HI
Find the initial pH of the 0.175 M KOH solution.
Find the pH when 18 mL of 0.200 M HI have been added.
Find the pH when 63 mL of the 0.200 M HI have been added.
How many milliliters of 0.200 M HI must be added to reach the equivalence point?
What is the pH at the equivalence point?
Answer: Initial pH is 13.243
12.83
1.3
40ml
7
Explanation:
Just finished the test.
The student then takes a 1.00M stock solution of table sugar (sucrose C12H22O11) and mixes 0.305L of stock solution with additional distilled water to create a dilute solution with a total volume of 1.25L.
Explain how the student can determine the molarity of the resulting solution. Show a valid calculation for the final molarity. PLS HELP
Answer: The molarity of final solution is 0.244 M.
Explanation:
Given: [tex]M_{1}[/tex] = 1.00 M, [tex]V_{1}[/tex] = 0.305 L
[tex]M_{2}[/tex] = ?, [tex]V_{2}[/tex] = 1.25 L
Formula used to calculate the molarity f resulting solution is as follows.
[tex]M_{1}V_{1} = M_{2}V_{2}[/tex]
Substitute the values into above formula as follows.
[tex]M_{1}V_{1} = M_{2}V_{2}\\1.00 M \times 0.305 L = M_{2} \times 1.25 L\\M_{2} = \frac{1.00 M \times 0.305 L}{1.25 L}\\= 0.244 M[/tex]
Thus, we can conclude that the molarity of final solution is 0.244 M.
A Chemist reacted magnesium and aluminum oxide. A reaction takes place. Explain why
Explanation:
when Magnesium is reacted with Aluminum oxide, Aluminum being a less reactive metal than magnesium, is replaced by magnesium
Al2O3 + 3Mg - 3MgO + 2Al
hence reaction takes place
When the temperature of the water was 10°C the waterweed did not produce bubbles.
Suzi increased the temperature of the water in the water-bath to 20°C. The waterweed started to produce bubbles.
She waited two minutes before starting to count the bubbles.
Explain why she waited for two minutes before she started to count the bubbles.
Science
Explanation:
she could waited for the saturated vapour pressure to equal the prevailing atmospheric pressure
ergo boiling to take place seeing as she had gotten the first indication that boiling had started
1. For the reaction below, which change would cause the equilibrium
to shift to the right?
CH,(g) + 2H,S(g) + heat --
CS,(g) + 4H,(g)
(a) Decrease the concentration of H,S.
(b) Increase the pressure on the system.
(c) Increase the temperature of the system.
(d) Increase the concentration of CS,
(e) Decrease the concentration of CH.
option c is the correct answer
because the gas there will be evolved and caused the equilibrium to shift to right side