Answer:
Observational evidence is essential for investigating the way disease affects populations, the patterns and distribution of risk within them, and the emergence of trends in health and disease over time.
Answer:
It tests a prediction It supports the results. It asks a testable question It predicts what will happen
Explanation:
Can salt dissolve in hydrogen peroxide? Pls help me
Answer:
Yes it can!!
Explanation:
Hydrogen peroxide mixed with sodium is known as oxygen bleach. Add water and the compound releases an oxygen molecule to help it lift mold and stains from the surface of natural materials.
The total thermal energy of a system depends jointly on the temperature, total number of in the system _______________, and the _______________of the material. *
1. Molecules/State
2. Molecules/Heat
3. Matter/Heat
4. Atoms/State
Answer:
Molecules/State
Explanation:
We know from the kinetic molecular theory that matter is made up of molecules. These molecules are in constant motion at various velocities and energies.
The total thermal energy refers to the total kinetic energies of these particles. It depends on the temperature of the system, the energies of the molecules present in the material and the arrangement of the object's molecules (states of matter).
To determine the concentration of citric acid, you will need to titrate this solution with 0.100 M NaOH. You are given a 1.00 M NaOH stock solution and will need to make enough 0.100 M NaOH to perform 3 titrations. For each titration, you will use 20.0 mL of 0.100 M NaOH solution.
Calculate the total volume (in mL) of the diluted solution you will need to prepare for the 3 titrations.
Determine the minimum volume (in mL) of 1.00 M NaOH stock solution needed to prepare the 0.100 M NaOH solution.
Answer:
60.0mL of the diluted solution are needed
6.00mL of the 1.00M NaOH stock solution is the minimum volume needed to prepare the diluted solution.
Explanation:
As in each titration we need to use 20.0mL of the diluted 0.100M solution. As there are 3 titration, the volume must be:
3 * 20.0mL = 60.0mL of the diluted solution are needed
Now, to prepare a 0.100M NaOH solution from a 1.00M NaOH stock solution the dilution must be of:
1.00M / 0.100M = 10 times must be diluted the solution.
As we need at least 60.0mL, the minimum volume of the stock solution must be:
60.0mL / 10 times =
6.00mL of the 1.00M NaOH stock solution is the minimum volume needed to prepare the diluted solution.How many moles are there in 24.0 grams of H2O
Answer:So, one mole of water has a mass of 16 +1+1 = 18 grams. So, if one mole has a mass of 18 grams, 25 grams would have a mass of 25 grams/ 18 grams per mole or 1.39 moles
Answer:
The answer would be 1.33
Explanation:
do you need an explanation?
URGENT!!! Compare the relative strength of the two forces A and B. Explain how you determined this comparison by identifying the forces
Answer:
A= Covalent bonding.
B = Dispersion forces.
Explanation:
This particular question wants to test our knowledge on chemical attractions in molecules. Kindly check the picture attached to get a glimpse of the two forces being compared here.
The force of attraction in B is known as the Dispersion forces. It is the kind of forces of attraction that happens when hydrogen bonds do not happen. Literarily, when Hydrogen atoms reacts with more electronegative atoms such as oxygen, Fluorine and Nitrogen, the kind of bond that will be formed will be an hydrogen bond. So, if hydrogen bond is not formed, then a weaker bond will be formed which is the Dispersion forces of attraction. Hence, B is the Dispersion forces.
Covalent bonds are the kind of bonds that involves that atoms shares electrons in order for chemical bonding to occur. Although, there is H2O which is a polar covalent bond. There are other compounds that are not polar such as CS2 and CH4. Therefore, the kind of attraction in A is covalent bonding.
What kind of solid tends to have the lowest melting points?
Answer:
Molecular solids
Covalent compounds
Explanation:
vote me as the brainliest
A compound with molecular formula C5H10Br2 displays the following 13C NMR along with the DEPT-90 and DEPT-135 13CNMR spectra. What is the structure for this compound?
Answer:
Explanation:
The correct structure for the compound C5H10Br2 is:
Br -- CH₂ -- CH₂ -- CH₂ -- CH₂ -- CH₂ -- Br
1 2 3 4 5
The name of the required compound is 1,5-dibromopentane.
The DEPT spectroscopy is applied to differentiate between CH₃, CH₂, and CH groups.
Assuming the DEPT is up, this shows a positive peak which illustrates CH₃ group
Assuming the DEPT is down, this shows a negative peak which illustrates CH₂ or CH group
C-13 NMR with DEPT-135
The negative peak in DEPT at 26.77 ppm illustrates CH₂ or CHThe negative peak at 31.85 ppm illustrate CH₂ or CHThe negative peak at 33.24 ppm illustrate CH₂ or CHThe carbon analysis is:
Assign ppm
1 33.24
2 31.85
3 26.77
4 31.85
5 33.24
Created when one substance is dissolved into another substance ? Is that a suspension. Solution or pure substance
Answer:
cemical change
Explanation:
Answer: A Solution
Explanation: A solution is made when a substance like salt is poured into water. The result would be a solution. Salt being a solid and water being a liquid.
Suppose a chemical engineer studying a new catalyst for the Haber reaction finds that liters per second of dinitrogen are consumed when the reaction is run at and the dinitrogen is supplied at . Calculate the rate at which ammonia is being produced. Give your answer in kilograms per second. Be sure your answer has the correct number of significant digits.
The question is incomplete. Here is the complete question.
In the Haber reaction, patented by German chemist Fritz Haber in 1908, dinitrogen gas combines with dihydrogen gas to produce gaseous ammonia. This reaction is now the first step taken to make most of the world's fertilizer. Suppose a chemical engineer studying a new catalyst for the Haber reaction finds that 505. liters per second of dinitrogen are consumed when the reaction is run at 172.°C and 0.88 atm. Calculate the rate at which ammonia is being produced. Give your answer in kilogram per second. Be sure your answer has the correct number of significant digits.
Answer: Rate = 0.41 kg/s
Explanation: The balanced Haber reaction is
[tex]N_{2}+3H_{2}\rightarrow2NH_{3}[/tex]
As all the components are gases, we can use Ideal Gas Law, which relates Pressure (P), Volume (V), Temperature (T) and Moles (n) in the following formula:
PV = nRT
where
R is gas constant and, in this case, is R = 0.082 L.atm.K⁻¹mol⁻¹
T is in Kelvin
Converting Celsius in Kelvin:
T = 273 + 172
T = 445 K
Calculating moles
[tex]n=\frac{PV}{RT}[/tex]
[tex]n=\frac{0.88(505)}{0.082(445)}[/tex]
n = 12.18 moles
According to the balanced equation, for 1 mol of dinitrogen gas consumed, 2 moles of ammonia is produced.
With 12.18 moles of dinitrogen, the reaction will result in
2(12.18) = 24.36 moles of ammonia
Molar mass of ammonia is M = 17.031 g/mol.
In 24.36 moles, there are
[tex]m=n.M[/tex]
m = 24.36.17.031
m = 414.87 grams
Since it's asking in kilograms: m = 0.41 kg.
In the beginning, it is said that dinitrogen gas is consumed at a rate of liters per second. So, the production rate of ammonia will be 0.41 kg/s.
How much heat must be used to raise the
temperature of 180. g water from 19° C to 96°C?
The specific heat of water is 4.18 J/gºC.
Answer:
Q = 57934.8 J
Explanation:
Given data:
Mass of water = 180.0 g
Initial temperature = 19°C
Fina temperature = 96°C
Specific heat capacity of water = 4.18 J/g.°C
Heat absorbed = ?
Solution:
Formula:
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
ΔT = 96°C - 19°C
ΔT = 77°C
Q = 180.0 g×4.18 J/g.°C×77°C
Q = 57934.8 J
Name the energy store that two electrical
charges have when they attract or repel each
other.
Answer:
In contrast to the attractive force between two objects with opposite charges, two objects that are of like charge will repel each other. That is, a positively charged object will exert a repulsive force upon a second positively charged object.
Explanation:
Hope it has answered your questionDraw the organic product(s) of the following reactions, and include carbon dioxide if it is produced.
CH3CH2-C triple bond C-CH2CH3 rightarrow O3
You do not have to consider stereochemistry.
If a compound is formed more than once, add another sketcher and draw it again.
Draw carbon dioxide in its own sketcher if it is produced.
Separate multiple products using the + sign from the dropdown menu.
If no reaction occurs, draw the organic starting material.
Answer:
See picture below
Explanation:
In this case, is ocurring an ozonolysis reaction with alkines.
Alkines, unlike alkenes, when they undergo an ozonolysis reaction, the product formed is a carboxilic acid. In some cases it may produce CO₂, but that will happen only if the starting molecule has a terminal Hydrogen atom.
In other words the following:
CH₃CH₂C≡CH
In this case, it may produces the CO₂. However, it's not the case, so it will produce two molecules of carboxylic acid.
You can see the picture below for the final product.
Hope this helps.
Alkynes are subjected to ozonolysis to produce two ketones or acid anhydrides. The acid anhydride undergoes hydrolysis to produce two carboxylic acids if water is present in the process. Elastomer ozonolysis is also referred to as the ozone method.
Ozone (O₃), a reactive allotrope of oxygen, is used in ozonolysis, a process for oxidatively breaking alkenes or alkynes. The procedure enables the substitution of double or triple carbon-carbon bonds with double oxygen bonds. This reaction is frequently used to determine an unknown alkene's structure.
The products of the given reaction can be shown below:
To know more about ozonolysis, visit;
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If you have 3.5 L of He to blow up balloons... at STP...
a) How many moles of He do you have?
b) How many grams of He do you have?
Answer:
B
Explanation:
When a substance undergoes a chemical change, its identity does not change.
O True
O False
Answer:
False
Explanation:
Chemists make a distinction between two different types of changes that they study—physical changes and chemical changes. Physical changes are changes that do not alter the identity of a substance. Chemical changes are frequently harder to reverse than physical changes.
Select one metal which will displace Sn from a compound and form metallic tin (Sn).
Cu, Cr, Ag, or Hg
Answer:
Cr
Explanation:
it just is im from Harvard my boy lmk
How many cm 3 are in 0.014 in 3? (1 in = 2.54 cm)
Answer:
0.229 cm³.
Explanation:
The following data were obtained from the question:
Volume (in in³) = 0.014 in³
Volume (in cm³) =?
1 in = 2.54 cm
Next, we shall determine a conversion scale to convert from in³ to cm³. This can be obtained as follow:
1 in = 2.54 cm
Therefore,
1 in³ = 2.54³ cm³
1 in³ = 16.387 cm³
Finally, we shall convert 0.014 in³ to cm³. This can be obtained as follow:
1 in³ = 16.387 cm³
Therefore,
0.014 in³ = 0.014 in³ × 16.387 cm³ / 1 in³
0.014 in³ = 0.229 cm³
Thus, 0.014 in³ is equivalent to 0.229 cm³.
what are some sources of error associated with electroplating
Answer:
Cold Shuts. Cold shuts are one of the most common defects found in materials sent for electroplating.
Pitting
Sharp Edges
Cleavage Points
Unclean Manufacturing
Loss of Adhesion
Cracking After Plating — Hydrogen Cracking
Dull and Hazy Deposits in Plating.
Explanation:
3. How much heat (in kl) is released when 1.65 mol NaOH(s) is dissolved in water? (The molar heat of solution of NaOH is -445.1 kJ/mol.)
a. -1.36x 10-3 kJ
b. -7.34 x 10^2 km
c. -2.69 x 10^1 km
d. -2.80 x 10^2 km
The heat released : b. -7.34 x 10² kJ
Further explanationGiven
1.65 mol NaOH
The molar heat of solution of NaOH is -445.1 kJ/mol
Required
Heat released
Solution
ΔH solution = Q : n
ΔH solution = enthalpy of solution(-=exothermic, +=endothermic)
Q = heat released/absorbed
n = moles of solute
Input the value :
Q = ΔH solution x n
Q = -445.1 kj/mol x 1.65 mol
Q = -734.415 kJ
How does the government rely on scientists?
If 1.546 g of copper was used by a student at the start of the lab, and 0.732 g of copper were obtained at
the end of the series of reactions, what was the percent recovery? Briefly explain how you found your
answer.
Answer: Percent recovery is 47.34 %
Explanation:
Percent yield is defined as the ratio of experimental yiled to theoretical yield in terms of percentage.
[tex]{\text{ percent yield}}=\frac{\text{amount recovered}}{\text{total amount}}\times 100[/tex]
Putting in the values we get:
[tex]{\text{ percent yield}}=\frac{0.732}{1.546}\times 100=47.34\%[/tex]
Therefore, the percent recovery is 47.34 %
A compound is made of 6.00 grams of oxygen, 7.00 grams of nitrogen, and 20.00grams of hydrogen. Find the percent composition of the compound.
A O-18.18%, N-21.21%, H-60.60%
B O-11.18%, N-22.21%, H-69.60%
C O-20%, N-30%, H-50%
D O-60.60%, N-21.21%, H-18.18%
The percent composition of the compound.
A O-18.18%, N-21.21%, H-60.60%
Further explanationGiven
6.00 grams of oxygen,
7.00 grams of nitrogen,
20.00 grams of hydrogen.
Required
The percent composition
Solution
Total mass :
= mass of O + mass of N + mass of H
= 6 + 7 + 20
= 33 g
% O = 6/33 x 100%= 18.18%
% N = 7/33 x 100%=21.21%
% H = 20/33 x 100% = 60.6 %
Classify each as acidic or basic - pH 9 - pH 2.3 - pH 11 - pH 5 - solution where the concentration of hydronium ions [H ] is 0.0056 M - solution where the concentration of hydronium ions [H ] is 3.45 E-9 M.
Answer:
pH = 9: Basic; pH = 2.3: acidic; pH = 11: basic; pH = 5: Acidic; [H⁺] = 0.0056M: Acidic; [H⁺] = 3.45E-9M: Basic
Explanation:
A solution is defined as acidic when pH < 7 and as basic when pH > 7.
Also, pH = -log[H⁺].
Thus:
pH = 9: >7 → Basic
pH = 2.3: <7 → Acidic
pH = 11: >7 → Basic
pH = 5: <7 → Acidic
[H⁺] = 0.0056M, pH = -log0.0056M = 2.25: <7: Acidic
[H⁺] = 3.45E-9M, pH = 8.46: > 7: Basic
When she introduced CO(g) and Cl2(g) into a 1.00 L evacuated container, so that the initial partial pressure of CO was 1.86 atm and the initial partial pressure of Cl2 was 1.27 atm, she found that the equilibrium partial pressure of COCl2 was 0.823 atm. Calculate the equilibrium constant, Kp, she obtained for this reaction.
Answer:
Kp is 0.00177
Explanation:
We state the equilibrium:
CO(g) + Cl₂(g) ⇆ COCl₂(g)
Initially we have these partial pressures
1.86 atm for CO and 1.27 for chlorine.
During the reaction, x pressure has been converted. As we have 0.823 atm as final pressure in the equilibrium for COCl₂, pressure at equilibrium for CO and chlorine will be:
1.86 - x for CO and 1.27 - x for Cl₂.
And x is the pressure generated for the product, because initially we don't have anything from it. So pressure in equilibrium for the reactants will be:
1.86 - 0.823 = 1.037 atm for CO
1.27 - 0.823 = 0.447 atm for Cl₂
Let's make, expression for Kp:
Partial pressure in eq. for COCl₂ / P. pressure in eq. for CO . P pressure in eq. for Cl₂
Kp = 0.823 / (1.037 . 0.447) → 0.00177
What is the structure formula of c10h18
Answer: I'm not 100% sure this is the formula but I hope it still helps! :)
Explanation:
Bornane; Cyclodecene; Decalin; Decynes. 1-Decyne; 2-Decyne; 3-Decyne; 4-Decyne; 5-Decyne, also known as dibutylethyne; Spirodecane
Find the mass in grams of 1.38 moles of Sr
Answer:
116.78 grams.
Explanation:
1 mol of Strontium (Sr) = 87.62 grams
1.38 mol of Strontium = x
Cross Multiply
1 * x = 1.38 * 87.62
x = 116.78 grams
what state of matter travels in straight lines
Answer:
light
Explanation:
light is plasma, which is a state of matter
You can use solid, wedged, and dashed lines to better represent the 3D structure of molecules. The solid lines represent bonds in the plane of the paper, wedged lines represent a bond coming out of the plane, and the dashed line represents a bond going back behind the plane of the paper. Draw a representation of methane that better depicts its 3D structure.
Answer:
See explanation and image attached
Explanation:
Often times, there is a need for a three dimensional representation of a molecule on paper. These three dimensional representations give us an idea of what the molecule really looks like if we were to be looking at it physically.
In order to make a three dimensional representation, we use wedged and dashed bonds. The wedged bonds are coming out of the plane of the paper towards you while the dashed bonds are going into the plane of the paper away from you.
In the image attached, you will find the three dimensional representation of the methane molecule.
Which nitrogen bases always pairs with thymine?
Answer:
The four different bases pair together in a way known as complementary pairing. Adenine always pairs with thymine, and cytosine always pairs with guanine.
Explanation:
I'll give you brainliest, if your answer is right :) Element A is in group 1A with a molar mass of 10 g/mol Element B is in group 7A with a molar mass of 30g/mol
a, A (solid) and B (gas) undergoes a combination reaction. Write the balanced chemical equation.
b, How many grams of B2 are needed to form a 2.5 M solution of AB with a volume of 250 mL?
Mass of B₂ = 18.75 g
Further explanationGiven
Element A and element B
Required
The reaction
mass of B₂
Solution
The balanced equation :
2A(s) + B₂(g) ⇒2AB(s)
mol AB :
= Molarity x Volume
= 2.5 M x 0.25 L
= 0.625
From the equation, mol ratio of B₂ : AB = 1 : 2, so mol B₂ :
= 1/2 x mol AB
= 1/2 x 0.625
= 0.3125
Mass B₂ (Molar mass = 2x30 g/mol=60 g/mol)
= mol x molar mass
= 0.3125 x 60 g/mol
= 18.75 g
Derive the isentropic and isothermal compressibility terms (for an ideal gas) in the most simplified form and compare them.
Answer:
Isothermal compressibility is different from isentropic compressibility by temperature instead of entropy.
Explanation:
Isothermal compressibility refers to that type of compressibility where volume change takes place at constant temperature whereas isentropic compressibility refers to that in which volume change takes place at constant entropy. Entropy is the measure of a thermal energy of the system per unit temperature that is unavailable for doing useful work.