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Write the symbol for every chemical element that has atomic number less than 14 and atomic mass greater than 23.2 u.
Answer:
8 oxygen. 9 flourine. 10. Neon. 5 Boron
An element of the environment that causes a population the decrease is
A) the birthrate minus the death rate
B) the carrying capacity
C) a limiting factor
D) the death rate
11th grade chemistry question will mark brainliest
2.50 g of CO2 gas is confined in a rigid cylinder at a pressure
of 4.65 atm. If 0.42 g of gas is released from the cylinder,
what is the new pressure?
Answer:
3.88 atm
Explanation:
We'll begin by calculating the number of mole of CO₂ in each case. This can be obtained as follow:
For 2.50 g of CO₂:
Mass of CO₂ = 2.5 g
Molar mass of CO₂ = 12 + (2×16) = 44 g/mol
Mole of CO₂ =?
Mole = mass / molar mass
Mole of CO₂ = 2.5 / 44
Mole of CO₂ = 0.06 mole
For 0.42 g of CO₂:
Mass of CO₂ = 2.5 g
Molar mass of CO₂ = 44 g/mol
Mole of CO₂ =?
Mole = mass / molar mass
Mole of CO₂ = 0.42 / 44
Mole of CO₂ = 0.010 mole
Finally, we shall determine the new pressure. This can be obtained as follow:
Initial mole (n₁) = 0.06 mole
Initial pressure (P₁) = 4.65 atm
Final mole (n₂) = 0.06 – 0.010 = 0.05 mole
Final pressure (P₂) =?
NOTE: Temperature and volume is constant.
P₁ / n₁ = P₂ / n₂
4.65 / 0.06 = P₂ / 0.05
Cross multiply
0.06 × P₂ = 4.65 × 0.05
0.06 × P₂ = 0.2325
Divide both side by 0.06
P₂ = 0.2325 / 0.06
P₂ = 3.88 atm
Thus, the new pressure is 3.88 atm.
A dilute solution of an unknown ionic compound must be identified. Several experiments are run on solutions that contain the possible ions with the results tabulated below. Cation Addition of HCl Heated in hot water Ag+ White precipitate is formed No observable change Pb+2 White precipitate is formed Precipitate dissolves Zn+2 No observable change No observable change Anion Addition of Ca(NO3)2 Addition of HNO3 CO3–2 White precipitate is formed Precipitate dissolves and bubbles form PO4–3 White precipitate is formed Precipitate dissolves A white precipitate is formed when HCl is added to the unknown compound. When the white precipitate is heated in hot water, it does not dissolve. A white precipitate is formed when Ca(NO3)2 is added to the unknown compound. When HNO3 is added to the precipitate, it dissolves and bubbles are formed. What is the chemical formula of the unknown ionic compound?
Answer:
The chemical formula of the unknown ionic compound is Ag₂CO₃.
Explanation:
The method used to identify the ions present in a given solution of an unknown compound is known as qualitative analysis. Specific tests are carried based on the chemical reaction of these ions and the results they give in these reactions, the ions present innthe compound are identified. Some of the results or observations include formation of precipitates on addition of certain reagents, evolution of gases, colour changes, as well as the color changes that are observed in a flame test of a solutionmof these compounds.
In the given question, when testing for cations, a white precipitate is formed when HCl is added to the unknown compound. When the white precipitate is heated in hot water, it does not dissolve.
From the table of observations, both Ag+ and Pb²+ give a white precipitate on addition of HCl but Zn²+ does not. So the cation present is either Ag+ or Pb²+. However, when heated in hot water, the white precipitate does not dissolve as will be observed if Ag+ were the cation present. Thus, the cation is Ag+.
When testing for anions, a white precipitate is formed when Ca(NO3)2 is added to the unknown compound and when HNO3 is added to the precipitate, it dissolves and bubbles are formed.
Now comparing these results with that as observed with CO₃²- and PO₄³-, both form white precipitates on addition of Ca(NO₃)₂, and the precipitate dissolves on addition of HNO₃. However, only CO₃²- dissolves with the production of bubbles when HNO₃ is added. Thus, the anion is CO₃²-.
Therefore, the compound is Ag₂CO₃ which is formed from the cation Ag+ and CO₃²-.
What is the molarity of a solution if 325ml of the solution contains 46.8 grams of NaHCO3?
Answer:
1.714 M
Explanation:
We'll begin by calculating the number of mole in 46.8 g of NaHCO₃. This can be obtained as follow:
Mass of NaHCO₃ = 46.8 g
Molar mass of NaHCO₃ = 23 + 1 + 12 + (3×16)
= 23 + 1 + 12 + 48
= 84 g/mol
Mole of NaHCO₃ =?
Mole = mass / molar mass
Mole of NaHCO₃ = 46.8 / 84
Mole of NaHCO₃ = 0.557 mole
Next, we shall convert 325 mL to L. This can be obtained as follow:
1000 mL = 1 L
Therefore,
325 mL = 325 mL × 1 L / 1000 mL
325 mL = 0.325 L
Thus, 325 mL is equivalent to 0.325 L.
Finally, we shall determine the molarity of the solution. This can be obtained as shown below:
Mole of NaHCO₃ = 0.557 mole
Volume = 0.325 L
Molarity =?
Molarity = mole / Volume
Molarity = 0.557 / 0.325
Molarity = 1.714 M
Therefore the molarity of the solution is 1.714 M
I don’t want to fail help
I need correct answer if u don’t know I will report
When the researcher compiled information which research method did they most likely utilize?
a) documentary
b) survey
c) participant observation
d) case study
Answer:
a
Explanation:
documentary is best researcher!.
When a photon of red light hits metal X, an electron is ejected. Will an electron be ejected if a photon of yellow light hits metal X?
A. Yes
B. No
C. Can't tell
How do I answer the question in bold? Thank you!
Answer:
6.7855 * 10^18
Explanation:
There are 2 moles in H2
Avagadro's number: 6.022E23
8.14E42*1/6.022E23 * 1/2
=6.7855 * 10^18
Which elements are main-group elements?
1. Te
2. K
3. V
4. Re
5. Ag
Answer:
Te
K
Explanation:
Main group elements are elements designated and located on the s-block and p-block on the periodic table. The core group or prominent elements are the elements that make up those groups. These groupings comprise the most naturally rich and abundant elements. The main group elements are those whose characteristics are more predicted as a function of their periodic table location. From the given options, only Te and K are elements of the main-group.
༒How much does the earth weigh?☆☆☆☆☆☆☆☆☆☆☆☆
Answer:
Earth has a mass of 5.9736×1024 kg
5.972×10²⁴kghope it is helpful to you
How many molecules are present in 1296 g of dinitrogen pentoxide (N2O5)
Answer:
The molar mass of N2O5 is 108 g/mol. 1296g of N2O5 has 1296 / 108 = 12 moles. 1 mole contains 6.022 x 10^23 molecules
what class of organic compound is formed when cyclopentanone reacts with ethylamine in the presence of trace acid
The question is incomplete, the complete question is;
What functional group results when cyclopentanone reacts with ethylamine in the presence of trace acid? A) cyanohydrin B) semicarbazone C) imine D) enamine E) oxime
Answer:
imine
Explanation:
An imine is an unsaturated amine. An imine contains the carbon- nitrogen double bond.
Imines are obtained when a carbonyl compound is condensed with NH3 or an amine. The reaction involves several steps in its mechanism.
Since cyclopentanone is a ketone (carbonyl compound) and ethylamine is an amine,in the presence of trace acid, condensation of the two compounds occur to yield an imine
During a reaction, ΔH for reactants is −750 kJ/mol and ΔH for products is 920 kJ/mol. Which statement is correct about the reaction? (5 points)
Group of answer choices
It is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
It is exothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
It is exothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
Answer: The statement it is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed, is true.
Explanation:
A chemical reaction in which heat energy is released is called an exothermic reaction. For exothermic reactions, the value of [tex]\Delta H[/tex] is always negative.
A chemical reaction in which heat energy is absorbed is called an endothermic reaction. For endothermic reaction, the value of [tex]\Delta H[/tex] is always positive.
In endothermic reactions, energy required for breaking the bonds between reactants is less than the energy when products are formed due to which the value of [tex]\Delta H[/tex] remains positive.
Thus, we can conclude that the statement it is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed, is true.
It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed. The correct option is B.
The above reaction is endothermic because more energy is produced when new bonds form in the products (H = 920 kJ/mol) than is required to break bonds in the reactants (H = -750 kJ/mol).
In an endothermic process, more energy than is generated during bond creation is absorbed from the environment to dissolve existing bonds. This causes a net absorption of energy, which cools the system.
The reaction takes more energy than it releases, proving its endothermic nature, as seen by the positive difference between the energy needed to dissolve bonds and the energy released during bond formation.
Thus, the correct option is B.
For more details regarding endothermic process, visit:
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Your question seems incomplete, the probable complete question is:
During a reaction, ΔH for reactants is −750 kJ/mol and ΔH for products is 920 kJ/mol. Which statement is correct about the reaction? (5 points)
Group of answer choices
A. It is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
B. It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
C. It is exothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
D. It is exothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
Draw the major product that is obtained when (2S,3S)-2-Bromo-3-phenylbutane is treated with sodium ethoxide.
Answer:
Explanation:
The mechanism of the reaction is shown in the diagram below. From the reaction, when (2S,3S)-2-Bromo-3-phenylbutane undergoes a reaction with sodium ethoxide (ETONa), the E2 elimination reaction is put into place. Here, the H and the leaving group are antiperiplanar to one another and the reaction mechanism proceeds to form an isomeric (E)-2-phenyl-2butane as the major product.
An object was measured by a worker as 14.6cm long, however, the manufacturer specifications list the length of the object at 14.4cm. What is the percent error in the worker's measurement? A. 1.39%
B. 1.37%
it's 0.2cm different from the expected value, wich was 14.6cm
how many percent that are is calculated in the screenshot.
rounded it's 1.37%
The boiling point of a liquid is 50°C. What is this temperature on the Kelvin scale?
Answer:
323.15 or just 323 depending on the teacher
(4.184 J——> 1 calorie ? Take your answer from number 1 and convert to the answer into calories?
Answer:
There are 1.195 calories in 5 J.
Explanation:
The relation between calorie and Joules is as follow :
4.184 J = 1 calorie
or
1 J = (1/4.184) calorie
Let the taken number is 5 J
So,
5 J = (5/4.184) calorie
5 J = 1.195 calorie
So, there are 1.195 calories in 5 J.
Which is a property of all bases?
Answer: The property of all bases is that they are substances which neutralizes an acid to form a salt and water only.
Explanation:
A base is also s substance that can accept or combine with a proton; a proton acceptor.
Bases include the oxides, hydroxides and carbonates of metals. These include MgO,Na2O, NaOH,Ca(OH)2. Most metals burn in oxygen to form metallic oxides which are basic. Examples are the MgO and Na2O.
Other properties or characteristics of bases includes:
--> They have a bitter taste.
--> They turn red litmus paper blue.
--> They are soapy to touch.
--> Aqueous solutions of bases are also electrolytes. Bases can be either strong or weak, just as acids can.
Bases (sodium hydroxide) can be used in the preparation of soaps, glass, paper and rayon. While some bases (magnesium hydroxide) can also be used to manufacture toothpaste and laxatives.
i.What are organic fertilizers?
ii.State three advantages of organic fertilizers over inorganic fertilizers.
Answer:
Organic fertilizers are those fertilizers that are not artificially produced but are natural and has carbon in them.
Fertilizers in the broad term are used to provide nutrient to the soil and boost growth of crops.
Some of the advantages of organic fertilizers to inorganic fertilizers are:
They do not make crusts on the soil, unlike inorganic fertilizers.
They help add structure to the soil because of the good water movement into the soil
They are easier on the soil because they feed good microbes.
Which probing question lies within the scope of physics?
O A.
Are fish in the open ocean
attracted by underwater sounds?
O B.
Does increasing the saltiness of
ocean water affect the speed
of sound in the water?
O C.
What effect does the release of industrial wastewater have on
the acidity of oceans?
D. What is the effect of rising sea temperatures on
ocean currents?
Answer:
answer number C is the correct answer for this
2x^2+8x-7 solve the equation
Answer:
x = (-4 + √30) / 2, or x = (-4 – √30) / 2
Explanation:
x = (-b ± √b² – 4ac) / 2a →
y = ax² + bx + c
given
y = 2x² + 8x – 7 →
x = (-(8) ± √(8)² – 4(2)(-7)) / 2(2) →
x = (-8 ± √64 + 56) / 4 →
x = (-8 ± √120) / 4 →
x = (-8 ± 2√30) / 4 →
x = (-4 ± √30) / 2 →
x = (-4 + √30) / 2, or x = (-4 – √30) / 2
How many grams of solute are present in 635mL of 0.450 M KBr?
Answer:
34.03 g
Explanation:
We'll begin by converting 635 mL to L. This can be obtained as follow:
1000 mL = 1 L
Therefore,
635 mL = 635 mL × 1 L / 1000 mL
635 mL = 0.635 L
Thus, 635 mL is equivalent to 0.635 L
Next, we shall determine the number of mole of the solute (KBr) in the solution. This can be obtained as follow:
Volume = 0.635 L
Molarity = 0.450 M
Mole of KBr =?
Mole = Molarity × Volume
Mole of KBr = 0.450 × 0.635
Mole of KBr = 0.286 mole
Finally, we shall determine the mass of 0.286 mole of KBr. This can be obtained as follow:
Mole of KBr = 0.286 mole
Molar mass of KBr = 39 + 80
= 119 g/mol
Mass of KBr =?
Mass = mole × molar mass
Mass of KBr = 0.286 × 119
Mass of KBr = 34.03 g
Thus, the mass of the solute (KBr) in the solution is 34.03 g
Please helpplease please..help
Answer:
vague symptoms are characteristic of an acute toxin, because of the of the lack of well defined consistency that these symptoms have in relation to the course of the disease progress.
in a breaker of water ,the water -water bonds can properly be called
Answer:
LICK
Explanation:
If 2.18 g of sodium peroxide (Na2O2) react with water to produce sodium hydroxide abs oxygen, how many liters of oxygen will be produced at 17.7 Celsius abs 726 torr?
Answer:
0.350 L
Explanation:
2Na₂O₂ + 2H₂O → 4NaOH + O₂First we convert 2.18 g of Na₂O₂ into moles, using its molar mass:
2.18 g ÷ 78 g/mol = 0.0279 mol Na₂O₂Then we convert 0.0279 moles of Na₂O₂ into moles of O₂, using the stoichiometric coefficients of the reaction:
0.0279 mol Na₂O₂ * [tex]\frac{1molO_2}{2molNa_2O_2}[/tex] = 0.0140 mol O₂Finally we use the PV=nRT formula to calculate the volume of oxygen produced:
P = 726 torrV = ?n = 0.0140 molR = 62.36 torr·L·mol⁻¹·K⁻¹T = 17.7 °C ⇒ 17.7 + 273.2 = 290.9 KInputting the data:
726 torr * V = 0.0140 mol * 62.36 torr·L·mol⁻¹·K⁻¹ * 290.9 KV = 0.350 Lg Calculate the percent yield when you start with 0.50 grams of salicylic acidand end with 0.33 grams of aspirin. The molecular weight of salicylic acid is 138.12 g/mol, and the molecular weight of aspirin is 180.157 g/mol.
Explanation:
hope the picture above helps you to understand:)
A compound that contains only carbon, hydrogen, and oxygen is 58.8% C and 9.87% H by mass. What is the empirical formula of this substance
Answer: The empirical formula of the compound becomes [tex]C_5H_{10}O_2[/tex]
Explanation:
The empirical formula is the chemical formula of the simplest ratio of the number of atoms of each element present in a compound.
Let the mass of the compound be 100 g
Given values:
% of C = 58.8%
% of H = 9.87%
% of O = [100 - 58.8 - 9.87] = 31.33%
Mass of C = 58.8 g
Mass of H = 9.87 g
Mass of O = 31.33 g
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
To formulate the empirical formula, we need to follow some steps:
Step 1: Converting the given masses into moles.Molar mass of C = 12 g/mol
Molar mass of H = 1 g/mol
Molar mass of O = 16 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of C}=\frac{58.8g}{12g/mol}=4.9 mol[/tex]
[tex]\text{Moles of H}=\frac{9.87g}{1g/mol}=9.87 mol[/tex]
[tex]\text{Moles of O}=\frac{31.33g}{16g/mol}=1.96mol[/tex]
Step 2: Calculating the mole ratio of the given elements.Calculating the mole fraction of each element by dividing the calculated moles by the least calculated number of moles that is 1.96 moles
[tex]\text{Mole fraction of C}=\frac{4.9}{1.96}=2.5[/tex]
[tex]\text{Mole fraction of H}=\frac{9.87}{1.96}=5.03\approx 5[/tex]
[tex]\text{Mole fraction of O}=\frac{1.96}{1.96}=1[/tex]
Converting the mole fraction into whole numbers by multiplying them with 2.
[tex]\text{Mole fraction of C}=2.5\times 2=5[/tex]
[tex]\text{Mole fraction of H}=5\times 2=10[/tex]
[tex]\text{Mole fraction of O}=1\times 2=2[/tex]
Step 3: Taking the mole ratio as their subscripts.The ratio of C : H : O = 5 : 10 : 2
Hence, the empirical formula of the compound becomes [tex]C_5H_{10}O_2[/tex]
The empirical formula of the substance is[tex]C_5H_{10}O_2[/tex].
Explanation:
Given:
A compound made up of 58.8% of carbon, 9.87% hydrogen, and oxygen.
To find:
The empirical formula of this substance.
Solution
The percentage of carbon in a given substance by mass = 58.8%
The percentage of hydrogen in a given substance by mass = 9.87%
The percentage of oxygen in a given substance by mass :
[tex]= 100\%-58.8\%- 9.87\%=31.33\%[/tex]
Consider 100 grams of a substance.
In 100 grams of substance:
The mass of carbon =58.8% of 100 g = 58.8 g
The mass of hydrogen = 9.87% of 100 g = 9.87 g
The mass of oxygen = 31.33% of 100 g= 31.33 g
The moles of carbon [tex]=\frac{58.8 g}{12.0107 g/mol}=4.90 mol[/tex]
The moles of hydrogen[tex]=\frac{9.87g}{1.00784g/mol}=9.79 mol[/tex]
The moles of oxygen[tex]=\frac{31.33g}{15.999g/mol}=1.96 mol[/tex]
let the empirical formula of the substance = [tex]C_xH_yO_z[/tex]
The value of subscript x:
[tex]=\frac{4.90 mol}{1.96 mol}=2.5[/tex]
The value of subscript y:
[tex]=\frac{9.79mol}{1.96 mol}=5[/tex]
The value of subscript z:
[tex]=\frac{1.96mol}{1.96 mol}=1[/tex]
The empirical formula of a substance :
[tex]C_{2.5}H_5O_1=C_{\frac{25}{10}}H_5O_1=C_{25}H_{50}O_{10}[/tex]
Reducing to the lowest whole numbers:
[tex]C_{25}H_{50}O_{10}=C_5H_{10}O_2[/tex]
The empirical formula of the substance is [tex]C_5H_{10}O_2[/tex].
Learn more about the empirical formula here:
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What is the theoretical yield of cyclohexene (in grams) that could be formed from 0.105 moles of cyclohexanol and 0.0444 moles of 85% phosphoric acid
Answer:
3.65 g of cyclohexene
Explanation:
Cyclohexanol + phosphoric acid ----> cyclohexene
The reaction is 1:1 hence the limiting reactant is phosphoric acid.
Hence,
1 mole of phosphoric acid yields 1 mole of cyclohexene
0.0444 moles of phosphoric acid yields 0.0444 moles of cyclohexene
Theoretical yield = number of moles of cyclohexene × molar mass of cyclohexene
Theoretical yield = 0.0444 moles of cyclohexene × 82.143 g/mol
Theoretical yield = 3.65 g of cyclohexene
Post-Lab Questions
1. A beverage company is having trouble with the production of the dye in their drinks. The color of their drink mix is supposed to be a pale green color, but they often get different results. For each unwanted result, choose the most plausible explanation to help the company improve the formula.
(1pts)
The color of the drink is too pale after adding the dye to the drink because
Choose...too much dye was added to the drink.the water in the drink is evaporating.not enough dye was added to the drink.the wrong dye was added to the drink.
(1pts)
The color of the dye is appearing as red, instead of green because
Choose...too much dye was added to the drink.the water in the drink is evaporating.not enough dye was added to the drink.the wrong dye was added to the drink.
(1pts)
The drink started out the correct color but it is getting darker over time, even though nothing has been added to the drink, because
Choose...too much dye was added to the drink.the water in the drink is evaporating.not enough dye was added to the drink.the wrong dye was added to the drink.
(1pts)
2. Beer's Law states that A=εbc, where A is the absorbance, ε is the molar absorptivity of the solute, b is the path length, and c is the concentration. Identify the experimental evidence from the activity that you have for the dependence of absorbance on each variable.
The evidence for the dependence of absorbance on the variable ε is
increasing the cuvette width increases the absorbance.
changing the compound changes the absorbance behavior.
adding more water decreases the absorbance.
Choose...ABC
(1pts)
The evidence for the dependence of absorbance on the variable b is
increasing the cuvette width increases the absorbance.
changing the compound changes the absorbance behavior.
adding more water decreases the absorbance.
Choose...ABC
(1pts)
The evidence for the dependence of absorbance on the variable c is
increasing the cuvette width increases the absorbance.
changing the compound changes the absorbance behavior.
adding more water decreases the absorbance.
Choose...ABC
(1pts)
3. Describe how you could use the Beer's Law simulation to experimentally determine the best wavelength at which to perform an experiment.
Measure the absorbance for solutions of multiple different solutes and find the minimum absorbance.
Measure the absorbance for solutions with different concentrations and find the slope of the trendline.
Measure the absorbance for the same solution at different wavelengths and find the maximum absorbance.
Measure the absorbance for the same solution in different cuvette sizes and find the y-intercept.
Answer:
1. not enough dye was added to the drink.
The wrong dye was added to the drink
the water in the drink is evaporating
2. Changing the compound changes the absorbance behavior.
3. Measure the absorbance for the same solution in different cuvette sizes and find the y-intercept.
Explanation:
When the beverage company adds dye to the drink, there should be standard quantity added to the drink so that the color of the drink remains constant. When too much dye is added to the drink, the color will get dark brown or black. When the color of drink get lighter than green this means dye is not added in required quantity.
The Li2+ ion is very similar to the hydrogen atom, in that it has one electron and energy levels similar
to the hydrogen atom. However, the relation = − (
1
2 −
1
2) cannot be used for this ion but
rather the relation = −2+ (
1
2 −
1
2) where the constant 2+=1.96x10-17J.
Use this relation to determine the third ionization energy, which is energy required to remove the last
electron from a Li2+ ion in kJ/mol, if the ion starts off in the ground state (Li2+ → Li3+
+ e-
).
