Answer:
after 45 days 9 g left
Explanation:
Given data:
Half life Na-24 = 15 days
Mass of sample = 72 g
Mass remain after 45 days = ?
Solution:
Number of half lives passed:
Number of half lives = time elapsed / half life
Number of half lives = 45 days / 15 days
Number of half lives = 3
At time zero total amount = 72 g
After first half life = 72 g/ 2= 36 g
At 2nd half life = 36 g/2 = 18 g
At 3rd half life = 18 g/2 = 9 g
Thus after 45 days 9 g left.
The IR spectrum of a sample contains absorptions at 3050, 2950, and 1620 cm-1. To what class of organic compound does this sample most likely belong
Answer:
Alkene
Explanation:
The IR spectrum of an organic compound shows us the functional groups present in the compound.
By looking at the various stretching frequencies given in wave numbers, we can decide what functional groups are in the compound and hence the class of organic compounds to which it belongs.
The stretch 3080 cm-1 shows a mono-substituted alkene
The stretch 2950 cm-1 shows a C-H bond
The stretch 1620 cm-1 shows an alkenyl stretch.
Hence the compound is an alkene.
Provide one example of how life on Earth would not be possible without water based on its characteristics.
Answer: ice is less dense than liquid water. If ice was more dense, Earth would freeze.
Explanation: There are many reasons why life on Earth depends on the characteristics of water. One could discuss hydrogen bonds and its role as a solvent, but the unusual property of water is is the change in density with change in temperature. Water is densest at 4 degC, which is why ice floats - it is less dense than cold water (it melts quickly in warm water, so density isn’t impotant at higher temperatures). Most liquids are less dense than the solid, frozen form. If this was the case with water, any ice that formed would sink, and sease would freeze from the bottom up. Furthermore, the lowest layers would be insulated and would not all melt in summer. Thus over time, the seas would become a thin layer of liquid water at best, over solid ice. Life could not develop without liquid seas. In addition, ice is reflective, reducing the amount of sunlight absorbed, further reducing temperatures. Without ocean circulation, polar areas would be even colder, and there would be no rain.
50 POINTS How many liters of O2 gas are in 4.21 moles?
and How many liters of PH3 gas are in 14.71 moles?
Explanation:
I mol of water = 22.4 lts of O2
thus, 4.21 moles of water = 4.21× 22.4= 94.304 lts.
what energy transfer and transformation occurs when riding a bicycle?
Answer: You pedaling the bike is transforming chemical energy
Explanation:
Islands have cool and calm weather throughout the year? Why?
A student is investigating potential and kinetic energy by stretching a spring across a table. When the student lets go
The spring recoils.
Answer: When the spring is recoiling
Explanation:
Answer:
When the spring is recoiling
Explanation:
How many grams are in 4.7 moles of Na2O?
290 g Na₂O
General Formulas and Concepts:Math
Pre-Algebra
Order of Operations: BPEMDAS
Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to RightChemistry
Atomic Structure
Reading a Periodic TableUsing Dimensional AnalysisExplanation:Step 1: Define
4.7 mol Na₂O
Step 2: Identify Conversions
Molar Mass of Na - 22.99 g/mol
Molar Mass of O - 16.00 g/mol
Molar Mass of Na₂O - 2(22.99) + 16.00 = 61.98 g/mol
Step 3: Convert
Set up: [tex]\displaystyle 4.7 \ mol \ Na_2O(\frac{61.98 \ g \ Na_2O}{1 \ mol \ Na_2O})[/tex]Multiply: [tex]\displaystyle 291.306 \ g \ Na_2O[/tex]Step 4: Check
Follow sig fig rules and round. We are given 2 sig figs.
291.306 g Na₂O ≈ 290 g Na₂O
2 points
A student saw the Moon rise at 6:20 a.m. on Monday. If he wants to see
the Moon rise again on Tuesday, vhat time should he look in the sky?(Mark
the one best answer.)
About 6:20 am
About 6:20pm
About 5:30 am
About 7:10am
how does mixture relate to your life
PLEAEEEE QUICKKKK AND FASTTT
what's the pH of a solution composed of 0.2 moles of NH3 and 0.15 moles of nh4cl
Answer:
[tex]pH=4.63[/tex]
Explanation:
Hello!
In this case, since the ionization of ammonia, which is a weak base, is written as:
[tex]NH_3+H_2O\rightleftharpoons NH_4^++OH^-[/tex]
We can see that the ammonium ion is the conjugate acid whereas the hydroxide ions the conjugate base; that is why we use the Henderson-Hasselbach equation to compute the pH, given the pKb of ammonia 4.75:
[tex]pH=pKb+log(\frac{[conj\ acid]}{[base]} )[/tex]
In such a way, for the given moles of ammonia, base, and those of ammonium chloride, conjugate acid form, we obtain:
[tex]pH=4.75+log(\frac{0.15}{0.2} )\\\\pH=4.63[/tex]
Best regards!
A student read an article about natural resources and listed some resources in the
chart shown. Which answer choice best classifies the natural resources in the chart?
Natural Resources
Coat
Air
Tree
Petroleum
Wheat
Natural
gas
Sheep
Lake
Fish
Answer:
Explanation:
Airs and trees
You have 11 blue cars, 7 red cars and 4 green cars
What percent of cars are green?
Answer to 1 Decimal Place (Check your rounding)
The density of benzene is 0.879g/mL. The volume (with 1 decimal) of 131.9g sample of benzene is how many mL?
Answer:
150.1 mL
Explanation:
Step 1: Given data
Density of benzene (ρ): 0.879 g/mLMass of the sample of benzene (m): 131.9 gVolume of the sample of benzene (V): ?Step 2: Calculate the volume of the sample of benzene
Density is an intrinsic property. It is equal to the quotient between the mass and the volume of the sample of benzene.
ρ = m/V
V = m/ρ
V = 131.9 g/(0.879 g/mL)
V = 150.1 mL
d. Calculate the initial reaction rate that would be seen in a solution in which [BF3] is 5.0 x10 -1M and [NH3] is 2.0 x10 -2 M
Answer:
[tex]r=0.0341\frac{M}{s}[/tex]
Explanation:
Hello!
In this case, considering the given table, we are able to represent the symbolic rate law as shown below:
[tex]r=k[BF_3]^m[NH_3]^n[/tex]
Thus, by using the following steps, we can find both m (BF3 order of reaction) and n (BF3 order of reaction):
- Experiment 1 and 2 for the calculation of n:
[tex]\frac{r_1}{r_2}=\frac{k[BF_3]_1^m[NH_3]_1^n}{k[BF_3]_2^m[NH_3]_2^n}[/tex]
So we plug in to obtain:
[tex]\frac{0.2130}{0.1065}=\frac{k*0.250^m*0.250^n}{k*0.250^m*0.125^n}\\\\2=\frac{0.250^n}{0.125^n}\\\\2=2^n\\\\log(2)=n*log(2)\\\\n=1[/tex]
So the order of reaction with respect to NH3 is 1.
- Experiment 3 and 4 for the calculation of m
[tex]\frac{r_3}{r_4}=\frac{k[BF_3]_3^m[NH_3]_3^n}{k[BF_3]_4^m[NH_3]_4^n}[/tex]
So we plug in to obtain:
[tex]\frac{0.0682}{0.1193}=\frac{k*0.200^m*0.100^n}{k*0.350^m*0.100^n}\\\\0.57=0.57^m\\\\log(0.57)=m*log(0.57)\\\\m=1[/tex]
So the order of reaction with respect to BF3 is also 1.
Now, we can compute the rate constant by solving for it on any of the experiments there, say experiment 1:
[tex]k=\frac{r_1}{[BF_3][NH_3]} =\frac{0.2130M/s}{0.250M*0.250M}\\\\k=3.41M^{-1}s^{-1}[/tex]
Thus, the initial reaction rate for the 0.50M BF3 and 0.020M NH3 is:
[tex]r=3.41M^{-1}s^{-1}*0.50M*0.020M\\\\r=0.0341\frac{M}{s}[/tex]
Best regards!
What reactive species is produced in the initiation step of the free radical chlorination of 2,2-dimethylpropane
Answer:
See explanation
Explanation:
An initiation step is the first step in a free radical mechanism. In this step, free radicals are generated from a stable compound. The initiation step tends to increase the concentration of radicals present in the system. It leads to a net increase in the number of free radicals in the system.
For the chlorination of 2,2-dimethylpropane, the initiation step is;
Cl2 + hv --------->2Cl.
Note that hv is used to represent light
How many hydrogen atoms are in 5 molecules of isopropyl alcohol, C3H7O ?
Answer:
The answer is "35 atoms".
Explanation:
The Formula for isopropyl alcohol is: [tex]C_3H_8O[/tex]
In 1 molecule of [tex]C_3H_8O[/tex] = 8 atoms of hydrogen
In 4 molecule of = atoms of hydrogen
According to the given formula [tex]C_3H_7O[/tex]
In 5 molecule of [tex]C_3H_7O[/tex] [tex]= 5 \times 7 = 35[/tex] atoms of hydrogen.
Which of the following best describes how water evaporates? *
3 points
A. Water molecules that move with higher energy evaporate first
B. Water molecules that are cooled evaporate
C. None of the above
A symbiotic relationship in which both organisms benefit
A. parasitism
B. mutualism
C. commensalism
Answer: B
Mutualism.
Explanation:
PLEASE HELP PLEASEEESSSS
Answer:
The answer is C or 3 which ever but it that one
Explanation:
Why is it important to have control???
Answer:
A control is important for an experiment because it allows the experiment to minimize the changes in all other variables except the one being tested.
Explanation:
do u mean that kind of control
Which of the following is NOT a major area of scientific study?
Answer:
Hate 2 break it 2 u foo but there's no option for me 2 choose....
Photosynthesis is? (Single choice)
A. chemical reaction that occurs in the mitochondria of a cell in all living organisms.
B. a chemical reactions that occurs in the chloroplast of a plant.
C. a chemical reaction that uses food molecules and converts it into ATP.
D. a chemical reaction that occurs mainly in protists.
Answer:
B. a chemical reactions that occurs in the chloroplast of a plant.
Explanation:
Answer:
B.
Explanation:
it is b because I took science
lol have a good day
If an object has a density of 25 g/cm and a mass of 100 grams, what is its volume? O 40 cm3 0.25 cm 4 cm3 125 cm3
4 cm³
General Formulas and Concepts:Math
Pre-Algebra
Order of Operations: BPEMDAS
Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to RightEquality Properties
Multiplication Property of Equality Division Property of Equality Addition Property of Equality Subtract Property of EqualityChemistry
Gas Laws
Density = Mass over Volume
D = m/V Explanation:Step 1: Define
D = 25 g/cm³
m = 100 g
Step 2: Solve for V
Substitute variables [D]: [tex]\displaystyle 25 \ g/cm^3 = \frac{100 \ g}{V}[/tex]Multiply V on both sides: [tex]\displaystyle V(25 g/cm^3) = 100 \ g[/tex]Isolate V: [tex]\displaystyle V = 4 \ cm^3[/tex]What happens at all convergent plate boundaries?
Explanation:
At convergent plate boundaries two plates are moving towards one another and different scenarios are in play.
Most importantly, at these margins the crust is being destroyed.
At continental - continental crust margin, there is an uplift because the density of the two crust is similar and lesser than that of the mantle below. At continental - oceanic crust margin, subduction zones are found where the denser oceanic crust sinks beneath into the mantle. This is also the case with ocean - ocean convergence zone.Some of the features found at this margin include, oceanic trenches, accretionary wedges, volcanic islands, earthquakes
Please help me thanks so much....I’ll mark you?!?!:))))
Answer:
chemical
Explanation:
Write a balanced equation describing the reduction of H2SeO4 by SO2 to produce selenium. (Use the lowest possible coefficients. Include states-of-matter under SATP conditions in your answer.)
Answer:
[tex]\mathbf{H_2SeO_{4(aq)} + 3SO_{2(aq)} + 2H_2O_{(l) } \to Se_{(s)} + 3H_2SO_{4(aq)} }[/tex]
Explanation:
We are to write a balanced equation from the information given above by including the states of their matter according to SATP conditions;
[tex]\mathbf{H_2SeO_{4(aq)} + 3SO_{2(aq)} + 2H_2O_{(l) } \to Se_{(s)} + 3H_2SO_{4(aq)} }[/tex]
From above;
The oxidizing agent is [tex]\mathbf{H_2SeO_{4(aq)} }[/tex]
The reducing agent is [tex]\mathbf{SO_{2(aq)} }[/tex]
Are the nuclei of all atoms
a) Positive
b) Negative
c) Neutral
11)
B.
A.
D.
Which position represents spring in the southern hemisphere?
A)
А
B)
B
C)
С
D)
D
Answer:
Cccccccccccccccccccccccccccccccccccccccccccc
A chemist adds of a calcium sulfate solution to a reaction flask. Calculate the mass in grams of calcium sulfate the chemist has added to the flask. Round your answer to significant digits.
The given question is incomplete. The complete question is:
A chemist adds 0.85 L of a 0.0050M calcium sulfate to a reaction flask. Calculate the mass in grams of calcium sulfate the chemist has added to the flask. Round your answer to significant digits.
Answer: The mass in grams of calcium sulfate the chemist has added to the flask is 0.58 g
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.
[tex]Molarity=\frac{n}{V_s}[/tex]
where,
n = moles of solute
[tex]V_s[/tex] = volume of solution in L
moles of [tex]CaSO_4[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{xg}{136g/mol}[/tex]
Now put all the given values in the formula of molarity, we get
[tex]0.0050=\frac{x}{136\times 0.85}[/tex]
[tex]x=0.58 g[/tex]
Therefore, the mass in grams of calcium sulfate the chemist has added to the flask is 0.58 g
HEY THIS ANSWER CORRECT ?
Answer:
I don't think that answer is right. I got 543.04 grams.
Explanation:
I think the question is asking for grams in the samlpe instead of the moles in the sample because it already gives you the amount of moles.