Answer:
A liquid freezes into a solid or any other state change is a physical change. Bubbles are produced upon mixing two solutions is a Chemical change as gas formed. a precipitate is formed from two solutions is a Chemical change The conversion of a substance to another compound over time leads to a color change of the substance due to the insolubility of the compound.
It is a chemical change or properties. A solution that heats up upon mixing with another is a Chemical change known as an exothermic reaction. dissolving the substance in a liquid is a physical change physical that can be regained by evaporation or crystalization.
Iron-59 which is used to diagnose anaemia has a half life of 45days, what fraction of it is left in 90 days
Answer:
0.25 of the original
Explanation:
(0.5)^(90/45)
The fraction of iron-59 after 90 days is 0.25.
Iron-59 decays following first-order kinetics. Given the half-life ([tex]t_{1/2}[/tex]) of 45 days, we can calculate the rate constant (k) using the following expression.
[tex]k = \frac{ln2}{t_{1/2}} =\frac{ln2}{45day} = 0.015 d^{-1}[/tex]
For first-order kinetics, we can find the fraction of Fe ([Fe]/[Fe]₀) after and an elapsed time (t) of 90 days, using the following equation.
[tex]\frac{[Fe]}{[Fe]_0} =e^{-k \times t } = e^{-0.015 d^{-1} \times 90 d } \approx 0,25[/tex]
The fraction of iron-59 after 90 days is 0.25.
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3. Una piedra que se tira verticalmente hacia arriba se mueve según la
leys = 64y - 8t^2, si "s" se mide en pies (ft) y t en segundos, hallar:
a) SU posición y velocidad después de dos segundos y después de tres
segundos.
b) ¿Qué altura alcanzará?
c) ¿A qué distancia se moverá al cabo del cuarto segundo?
Answer:
Explanation:
Para mejor entendimiento, reeescribiremos la ley que pusiste:
S = 64t - 8t² (1)
De acuerdo al enunciado del problema, S tiene unidades de pie y t en segundos, por lo tanto, S, que se refiere a la posición o altura alcanza de la piedra, puede ser determinado usando esa expresión a tiempos específicos.
Para el calculo de velocidad usamos la siguiente expresión:
V = -g * t (2) g: 32.16 ft/s
Tomando en cuenta estas expresiones, veamos los valores de posición y velocidad:
a) Para t = 2 s
S = 64(2) - 8(2)²
S = 96 ft
V = -32.16 * 2
V = -64.32 ft/s
Para t = 3 s
S = 64(3) - 8(3)²
S = 120 ft
V = -32.16 * 3
V = -96.48 ft/s
b) Para saber la altura que alcanzará, usamos la expresión de altura máxima que es la siguiente:
Smáx = -V₀² / 2g (3)
Para el valor de la velocidad inicial, podemos asumir el valor de la velocidad dada por la formula de la ley S, que es 64. Esto porque al ser multiplicado por el valor del tiempo, queda en unidades de distancia, asi que este valor debe tener unidades de velocidad. Reemplazando este valor en la expresión:
Smáx = -(64)² / 2 * 32.16
Smáx = 63.68 ft
c) Para esta parte, usamos nuevamente la formula de la ley S, usando t = 4 s y listo:
S = 64(4) - 8(16)
S = 128 ft
Espero te sirva
What are typical characteristics of metals
Answer:
Metals are lustrous, malleable, ductile, good conductors of heat and electricity. Other properties include: State: Metals are solids at room temperature with the exception of mercury, which is liquid at room temperature (Gallium is liquid on hot days).
Which word is best used as a synonym for scientific conclusions?
A.
explanations
B.
results
C.
data
D.
observations
Answer:
B
Explanation:
Not C or D becuase it is data would not show a conclusion and observations does show the conclsuion of the scientists. Not A becuase explanation does not mean they have data to support their conclusion. Therefore, it would be B becuase results show what was the effect of something and is often supported with data
Hope that helped :)
Number of moles In 52.3 g of C12H22O11
Answer:
0.1529mol
Explanation:
Number of mole = x mol
Mass = 52.3g
Molar Mass of Sucrose
(C = 12, H = 1, O = 16)
C12H22O11
(12×12)+(1×22)+(16×11)
144 + 22 + 176
342g/mol
Number of Mole = Mass given/Molar mass
Number of mole = 52.3/342
Number of mole = 0.1529mol
For the Alka-Seltzer example what is the independent variable
A:The time it takes for the tablets to dissolve in different temperatures of water
B:The temperature of the water in which a tablet is dissolved
Father, I come to you worn and weary from the hard times I have walked through recently. I come to you seeking your shelter where I know I can find security and rest in your shadow. Father, you are mighty. I know my circumstances are no match for Your great power. Father I place a healing of these people that they feel a conviction in there heart that they would turn from there wicked way and turn to you father. IN JESUS NAME AMEN
Answer:
Fact: There’s only one letter that doesn’t appear in any U.S. state name
And that is Q
Explanation:
someone help please this is due today!!?
Answer:
I think beaker three will take longer to boil since there is more water present,compared to the other beakers
The student is now told that the four solids, in no particular order, are calcium bromide (CaBr2), sugar (C6H12O6), benzoic acid (C6H5COOH), and sodium bromide (NaBr). Assuming that conductivity is correlated to the number of ions in solution, rank the four substances based on how well a 0.20 M solution in water will conduct electricity. Rank from most conductive to least conductive. To rank items as equivalent, overlap them.
Answer:
Explanation:
Both calcium bromide and sodium bromide are ionic in nature so they will generate ions when dissolved in water .
CaBr₂ = Ca⁺² + 2Br⁻¹
NaBr = Na⁺ + Br⁻
Calcium bromide will generate greater number of ions per molecule according to chemical equation given above .
Benzoic acid ionizes but partially . Suger is a purely covalent compound so it does not generate ions at all .
In view of statement written above , the compounds can be arranged as follows according to conductivity from most to least conductive .
calcium bromide > sodium bromide > benzoic acid > sugar .
Which resource is a direct ecosystem service?
O food crops
O fresh water
O biodiversity
O land development
Answer:
Fresh Water is your answer
Fresh water is a direct ecosystem service. Therefore, the correct option is option B among all the given options.
What is ecosystem?An ecosystem, also known as an ecological system, is made up of all the creatures and the physical setting in which they live. The nutrition cycles and energy fluxes connect these both biotic and abiotic elements. Photosynthesis is how energy enter the system and is absorbed by plant tissue.
Animals play a significant part in the transfer of materials and energy through the system by eating plants and one another. They also have an impact on the biomass levels of the microbial and plant communities. Fresh water is a direct ecosystem service.
Therefore, the correct option is option B.
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What is the major organic product obtained from the reaction of 2,2-dimethyl-1-propanol aqueous HBr at reflux
Answer:
See explanation
Explanation:
The mechanism involves SN1 nucleophilic substitution reaction. The -OH group of the alcohol is first protonated. Since water is a good leaving group, -OH2 leaves the substrate creating a primary carbo cation.
A 1,2 methyl shift now occurs to create a tertiary carbo cation which is more stable leading to the major product shown in the image attached to this answer.
Calculate the number of moles of H2SO4 required to react with 0.93 moles of Al. Do not include units in your answer. Round to the tenths place or further.
Answer:
1.40 moles of H₂SO₄.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is illustrated below below:
2Al + 3H₂SO₄ —> Al₂(SO₄)₃ + 3H₂
From the balanced equation above,
2 moles of Al reacted with 3 moles of H₂SO₄.
Finally, we shall determine the number of mole of H₂SO₄ required to react with
0.93 moles of Al. This can be obtained as follow:
From the balanced equation above,
2 moles of Al reacted with 3 moles of H₂SO₄.
Therefore, 0.93 moles of Al will react with = (0.93 × 3)/2 = 1.40 moles of H₂SO₄.
Thus, 1.40 moles of H₂SO₄ is needed for the reaction.
After the reaction mixture is added to the top of the silica gel column, the instructions state: "Open the stopcock and drain the column until the meniscus is just above the top layer of the material. Add another 0.5 mL of solvent and repeat the process toensure that all of the desired products are adsorbed onto the silica gel. This process ensures that none of the desired products are dissolved in solution above the column."Why is this procedure important? How would the TLC plates look different than your prediction in Q1 if a student skipped this step?
Answer:
Kindly check the explanation section.
Explanation:
Without mincing words let's dive straight into the solution to the question.
The instructions given in the question above is very important as it concerns the total adsorption of the product on the silica gel. The instruction is made so that adsorption of the product is on the silica gel so as to avoid the distortion in polarity of the compound.
Part B.
If the student avoid the step, there would be problem of which the compound which is in mixture will be running out of the column. Also, the compounds won't be made pure.
In summary, for the first part adsorption is done on the silica gel thus, the instructions is to be followed.
For the second part, if the step is not avoided then the Compounds will be made pure if the step
describe what movement causes an electric current in a wire
Answer:
An electrical phenomenon is caused by flow of free electrons from one atom to another. The characteristics of current electricity are opposite to those of static electricity. Wires are made up of conductors such as copper or aluminum.
Explanation:
:)
How many minutes are in 230 seconds?
Answer:
230 Seconds = 3.83333333 Minutes
Explanation:
Answer:
3 minutes and 50 seconds
Explanation:
If there are 60 seconds in 1 minute..
60, 120, 180 (1 minute, 2 minutes, 3 minutes)
230 - 180 = 50
So it's 230 seconds consists of 3 minutes and 50 seconds.
How many grams of CaO can be produced using 3.9 moles CaCO3?1
CaCO3 --> 1CaO + 1CO *
Answer: 218.4 g of [tex]CaO[/tex] will be produced from 3.9 moles of [tex]CaCO_3[/tex]
Explanation:
The balanced chemical equation is:
[tex]CaCO_3\rightarrow CaO+CO_2[/tex]
According to stoichiometry :
1 mole of [tex]CaCO_3[/tex] produce = 1 mole of [tex]CaO[/tex]
Thus 3.9 moles of [tex]CaCO_3[/tex] will produce=[tex]\frac{1}{1}\times 3.9=3.9moles[/tex] of [tex]CaO[/tex]
Mass of [tex]CaO=moles\times {\text {Molar mass}}=3.9moles\times 56g/mol=218.4g[/tex]
Thus 218.4 g of [tex]CaO[/tex] will be produced from 3.9 moles of [tex]CaCO_3[/tex]
218.4 grams of CaO is produced using 3.9 moles CaCO₃.
How we calculate weight of any substance from moles?Moles of any substance will be define as:
n = W / M
Given chemical reaction is:
CaCO₃ → CaO + CO₂
From the above equation it is clear that according to the concept of stoichiometry 1 mole of CaCO₃ is producing 1 mole of CaO. By using above formula we calculate grams as follow:
W = n × M, where
n = no. of moles of CaO = 3.9 moles
M = molar mass of CaO = 56 g/mole
W = 3.9 × 56 = 218.4 g
Hence, 218.4 grams of CaO is produced.
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Determine the number of molecules of OF2 and moles of fluorine contained in 5.53 moles of OF2.
Answer: [tex]33.31\times 10^{23}[/tex] molecules of [tex]OF_2[/tex]
and 11.06 moles of Flourine
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.
1 mole of [tex]OF_2[/tex] contains= [tex]6.022\times 10^{23}[/tex] molecules of [tex]OF_2[/tex]
Thus 5.53 moles of [tex]OF_2[/tex] contains=[tex]\frac{6.022\times 10^{23}}{1}\times 5.53=33.31\times 10^{23}[/tex] molecules of [tex]OF_2[/tex]
1 mole of [tex]OF_2[/tex] contains= 2 moles of Flourine
5.53 moles of [tex]OF_2[/tex] contains=[tex]\frac{2}{1}\times 5.53=11.06[/tex] moles of Flourine
Is nitric acid a strong or weak acid. Explain your answer.
Answer:
Examples of strong acids are hydrochloric acid (HCl), perchloric acid (HClO4), nitric acid (HNO3) and sulfuric acid (H2SO4). A weak acid is only partially dissociated, with both the undissociated acid and its dissociation products being present, in solution, in equilibrium with each other.
Explanation:
Hope this helps you
Select the option that best represents recycling food waste
O turning food scraps into biogas
O donating unused food to food pantries
O incinerating leftover food
O feeding scraps to livestock
Answer:
feeding leftover or scraps to livestock
Explanation:
Because feeding leftover healthy food instead of leaving livestock to eat garbage is good for health of the animals and they give good quality of milk, eggs, meat, etc in return
You are a forensic scientist who has been asked to test two blood samples. You know that one sample is suspected of containing barbiturates and the other contains no drugs; however, you cannot tell the two samples apart. Describe in one - two paragraphs how you would use the concept of pH to determine which sample contains barbiturates. Explain your reasoning
Answer:
I will find the different between the samples
Please balance the equation, putting the correct coefficient in each box.
Do not leave any boxes blank! Enter "1" for formulas having a presumed
coefficient of 1.
Bi(OH)3 +
HNO3 →
H2O +
Bi(NO3)3
Answer: [tex]Bi(OH)_3+3HNO_3\rightarrow 3H_2O+Bi(NO_3)_3[/tex]
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced equation will be:
[tex]Bi(OH)_3+3HNO_3\rightarrow 3H_2O+Bi(NO_3)_3[/tex]
What volume of 0.130 M HCl is required for the complete neutralization of 1.30 g of NaHCO3 (sodium bicarbonate)?
Answer: Volume required is 0.115 L or 115 ml
Explanation:
moles of [tex]NaHCO_3[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{1.30g}{84g/mol}=0.015mol[/tex]
The balanced chemical equation is:
[tex]HCl+NaHCO_3\rightarrow NaCl+H_2CO_3[/tex]
1 mole of [tex]NaHCO_3[/tex] requires = 1 mole of HCl
Thus 0.015 mol of [tex]NaHCO_3[/tex] requires = [tex]\frac{1}{1}\times 0.015=0.015[/tex] mole of HCl
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
[tex]0.130=\frac{0..015}{V_s}[/tex]
[tex]V_s=0.115L[/tex]
Thus volume required is 0.115 l or 115 ml
Is energy absorbed or released during cellular respiration?
Absorbed
Released
Answer:
Released
Explanation:
they convert into a form of energy that can be used by cells
[50 Points] In the experiment below, Beaker 1 contains 12.0 M HCl. Each subsequent beaker is diluted by 50%. What is the [OH-] in Beaker 6?
Answer:
2.67x10⁻¹⁴M = [OH-]
Explanation:
To solve this question we need first to find the HCl concentration of the beaker 6. Then, using:
Kw = [OH-][H+]
Where Kw = 1x10⁻¹⁴
[OH-] is our incognite
[H+] is = [HCl]
Beaker 2 = 12.0M / 2 = 6.0M
Beaker 3 = 6.0M / 2 = 3.0M
Beaker 4 = 3.0M / 2 = 1.5M
Beaker 5 = 1.5M / 2 = 0.75M
Beaker 6 = 0.75M / 2 = 0.375M
HCl = 0.375M = [H+]
1x10⁻¹⁴ / [H+] = [OH-]
1x10⁻¹⁴ / 0.375M = 2.67x10⁻¹⁴M
2.67x10⁻¹⁴M = [OH-]In this simulation, there was no lid on the beaker to keep the steam from escaping. If the steam was trapped and it’s temperature was monitored, would you expect the temperature to increase or remain constant? Explain.
Answer:
Figure 1. In a calorimetric determination, either (a) an exothermic process occurs and heat, q, is negative, indicating that thermal energy is transferred from the system to its surroundings, or (b) an endothermic process occurs and heat, q, is positive, indicating that thermal energy is transferred from the surroundings to the system.
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Which equation is used to find the density of a solid?
mass + volume
mass * gravity
weight = gravity
volume * weight
Select the solute that is likely most soluble in hexane, C6H14-
Answer:
The solute that is most likely soluble in hexane is S₈
Explanation:
S₈ is a non-polar solute that exhibits the same characteristics and properties as hexane. Following the common principle "like dissolves like"; polar compounds will be soluble in polar solvents while non-polar compounds will be soluble in non-polar solvents. As such, since S₈ is non-polar, then it will be soluble in hexane.
A student adds an alka-seltzer to the Koolaid and stirs. The pH meter now reads 8.3. What was released by the alka-seltzer tablet to cause this change?
Answer:
It released hydroxide ions (OH ¯).
Explanation:
A PH of 8.3 indicates that the solution has become a basic solution.
Now, for us to have a basic solution from the addition of an alka-seltzer to Koolaid, it means the Alka-seltzer released plenty of hydroxide ons (OH¯) to the solution.
5. Why are lonic compounds good conductors of electricity?
lone compounds are electrical in nature
"The strong electrostate attraction between lons allow electricity
Aques solutions of lonie compounds cause to dissociate fons
are free to conduct electricity
de electrostate attraction between crystal lattice of
pound is strong which needs high temperature to melt arb
CO Q2 Science ?
Answer:
The options are unclear, however, the correct option is:
Aqueous solutions of ionic compounds cause to dissociate, hence, ions are free to conduct electricity
Explanation:
Ionic compounds are compounds formed from ions (charged atoms). For example, NaCl is an ionic compound from the following ions; Na+ (cation) and Cl- (anion). One characteristics of ionic compounds is their ability to dissociate into the ions that form them when in an aqueous solution i.e. NaCl will dissociate into Na+ and Cl- when in an aqueous solution.
These disssociated ions are free to conduct electricity, hence, making ionic compounds good conductors of electricity.
In the hot climate, human bodies had to adapt by increasing the number of ____________ on the skin to cool off the body.
A. Body hair
B. Sweat Glands
C. UV rays
D. None of the above
Answer:
body hair
Explanation:
in the hot climate,human bodies had to adapt inscrasing the number of bodyhair on the skin to coll off the body
