how was potassium discovered?
Answer:
Potassium was the first metal to be isolated by electrolysis. It was discovered by the English chemist Sir Humphry Davy by decomposing molten potassium hydroxide (KOH) with a voltaic battery.
Explanation:
Potassium was discovered by the English chemist Sir Humphrey Davy.
What is the name of the systematic approach that scientists use to understand the natural world?
a law
the scientific method
a hypothesis
a theory
It would be due to the scientific method
Hope this helps :)
A scientist observed that in the presence of light, plants use carbon dioxide and water to make glucose and oxygen. This chemical process is called photosynthesis. Which type of energy is transformed into chemical energy, based on the scientist's observations? Answer options with 4 options A. light energy from the sun B. kinetic energy from water C. chemical energy from oxygen D. heat energy from the environment
Answer:
Option A, light energy from the sun
Explanation:
In the process of photosynthesis, the energy from sun in the form of light and heat is taken to undergo glycolysis and prepare glucose/starch (chemical).
Thus, the light and heat energy of sun is converted into the chemical energy.
Option B and C are incorrect because no kinetic energy or chemical energy is taken from any source.
Option D is also incorrect because heat is taken but it is not taken from the surrounding environment. The source of heat energy is sun.
Thus, only option A is correct
The amount of ascorbic acid, C6H8O6. in orange juice was determined by oxidizing the ascorbic acid to dehydroascorbic acid, C6H6O6. with a known excess of l2, and back titrating the excess I2 with Na2S203. A 5.00-mL sample of filtered orange juice was treated with 50.00 mL of excess 0.01023 M l2. After the oxidation was complete, 13.82 mL of 0.07203 M Na2S203 was needed to reach the starch indicator endpoint. Report the concentration of ascorbic acid in milligrams per 100
mL
There is 2.43 mg of ascorbic acid in the 5.00-mL sample, or 48.6 mg/100 mL of orange juice.
Explanation:
For i2+na2s2o3 titration,
I2 + 2 S2O3^-2 <--> 2 I^-1 + S4O6^-2
13.82 mL of 0.07203 M Na2S2O3 was needed to reach the starch indicator end point.
Number of moles of Na2S2O3 = 13.82*0.07203= 0.9954546 millimoles.
So, number of moles of excess I2 = 0.9954546/2 = 0.4977273 millimoles.
For oxidizing the ascorbic acid to dehydroascorbic acid
C6H8O6 + I2 --> C6H6O6 + 2 H+ + 2 I-
SO 1mole of I2 read for 1 mole of C6H8O6.
Initial I2 used = 50*0.01023 = 0.5115 millimoles.
Number of moles of I2 used = 0.5115 - 0.4977273 = 0.0137727 millimoles.
Number of moles of C6H8O6 in5 ml of orange juice = 0.0137727 millimoles.
Weight of C6H8O6 in5 ml of orange juice = number of moles * molecular weight = 0.0137727 * 176 = 2.4239952 mg
In 100 ml of orange juice = 2.4239952/5) *100 = 48.479904 milligrams per 100 mL. is the answer.
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How many grams of KI are dissolved in 250 grams of 20% solution?
Answer:
180 g
Explanation:
how could you use this pattern to predict how the element may behave in a chemical reaction
Answer:
it can predict the properties of new elements, because it organizes the elements according to their atomic numbers.
Creating new elements is not a simple process. Scientists use a particle accelerator to smash light atoms into a thin metallic foil that contains heavier atoms. They hope that the two nuclei at the centre of these atoms will fuse and form a heavier nucleus.
When these heavy elements form, they are usually highly unstable. They decay so quickly that we don’t usually see the element itself. Instead, we see a decay product. In that respect, even new elements aren't always 'discovered' directly. In some cases, scientists haven’t synthesized enough of the element for us to know what the element even looks like! Nevertheless, we consider the elements as known. We name them and list them the periodic table.
For example, in 2003, scientists first observed element 115 (ununpentium, Uup) They bombarded americium-243 with calcium-248 ions and produced four atoms of Uup, which lived for less than one fifth of a second.
₂₀ ⁴⁸Ca + ₉₅²⁴³Am → ₁₁₅²⁸⁸Uup + 3 ₀¹n
It took until September 2013 for the discovery to be confirmed, and about 50 atoms have been synthesized to date.
We can predict the properties of Uup because the Periodic Table organizes elements according to their atomic number.
16. What are the two types of mixtures?
Heterogeneous and homogeneous mixtures are the two types of mixtures.
How to define the heterogeneous and homogeneous mixtures?When compared to homogeneous mixtures, heterogeneous mixtures can be visually divided into individual components. The most prevalent kind of homogeneous mixture is a solution, which can be a solid, liquid, or gas.
Solid, liquid, or gaseous homogeneous mixtures can exist. They are uniform in both appearance and chemical make-up. Water, air, steel, detergent, saltwater mixture, and other substances are examples of homogeneous mixtures. When two or more metals are combined in a specified proportion, an alloy is created.
A combination is said to be heterogeneous if its composition is not constant throughout. Vegetable soup is a complex concoction.
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2CH4O + 3o2 = 2CO2+ 4H20 (1)
ΔΗ =-726 kj
How many kilojoules are released when 75 g of CH4O Reacts?
The amount of heat released when 75 g of CH4O reacts is -1705.64 kJ.
The equation given is the balanced equation for the combustion of methanol (CH4O) with oxygen to form carbon dioxide (CO2) and water (H20). The value of ΔΗ given (-726 kJ) is the enthalpy change for the reaction, which represents the amount of heat released or absorbed when the reaction occurs.
To calculate the amount of heat released when 75 g of CH4O reacts, we need to use the equation: q = n x ΔΗ where,
q is the heat releasedn is the number of moles of CH4O reacting ΔΗ is the enthalpy change for the reaction.We know that the molar mass of CH4O is 32.04 g/mol, so we can convert 75 g to moles using the following formula: n = m/M where,
n is the number of molesm is the mass of CH4O M is the molar mass of CH4O.So, n = 75 / 32.04 = 2.34 moles
Using this value of n in the equation above, we can calculate the heat released as q = 2.34 x -726 = -1705.64 kJ
Therefore, -1705.64 kJ of heat is released when 75 g of CH4O reacts.
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How would you name this organic compound?
I found a couple ways to name it but I don't know which one's correct.
Which of the following properties can be used to describe both the particle model of light and the wave model of light
An absolutely interesting occurrence is light. Despite the fact that it is well recognized that light is an electromagnetic, it is frequently more practical to characterise or characterize light in other ways than only as a wave.
For instance, light is frequently depicted as anything other than a wave in spectroscopy and fundamental physics.
Similar to how we replicate oceans moving through water, the Wave Model illustrates how light propagates. Colors can be explained using the Wave Model by including information about wavelength.
The Light Wave Model. Similar to how we simulate ocean waves moving across water, the Wave Model illustrates how light propagates. We can explain qualities of light by imagining it to be an oscillating wave.
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PbO + NaOH →→
complete and balance the following formula
Answer:
Explanation:
Pb(OH)2 + 2NaOH → Pb(OH)2 + 2NaOH
The balanced equation would be PbO + 2NaOH → Pb(OH)2 + Na2O
The reactant PbO is a lead oxide which is an acidic oxide, it reacts with NaOH, a strong base, to form Pb(OH)2, a lead hydroxide, which is a salt of lead, and Na2O which is sodium oxide , a base.
What type of change in matter absorbs energy or requires energy?
A.)freezing
B.) condensation
C.)exothermic reaction
D.)endothermic reaction
D.) endothermic reaction
List all the possible types of bonding for oxygen
Two covalent bonds are formed by oxygen to complete their octet.
What are covalent bonds?An electron exchange that results in the formation of electron pairs between atoms is known as a covalent bond. Bonding pairs or sharing pairs are the names given to these electron pairs. Covalent bonding is the stable equilibrium of the attractive and repulsive forces between atoms when they share electrons.
What is an octet?In chemistry, an octet is an arrangement of eight electrons in the outer electron shell of a noble gas atom. The relative inertness of noble gases and the chemical behaviour of several other elements are attributed to this structure.
What is oxygen?The chemical element oxygen has an atomic number of 8. (it has eight protons in its nucleus). At normal temperatures and pressures, oxygen transforms into the chemical compound (O2) of two atoms, which is a colourless gas.
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When using IR spectroscopy, what is being recorded by the machine?
Sizes
O Wavelengths
O Color
O Molecular mass
Answer:
wavelengths
Explanation:
hope it helps
thanks
Wavelengths are being recorded by the machine by using IR spectrography. Therefore, option B is correct.
Infrared (IR) spectroscopy is also known as infrared spectrometry. It is a technique that is used to analyze and identify chemical compounds based on their absorption or emission of infrared radiation.
Infrared radiation lies in the electromagnetic spectrum between visible light and microwave radiation. It has longer wavelengths and lower frequencies than visible light. When infrared radiation passes through a sample, certain chemical bonds in the sample absorb specific frequencies of infrared light.
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What is Fracking (Own Words)
The process of forcing liquid at high pressure into rocks, deep holes in the ground, etc. in order to force open existing cracks and take out oil or gas.
Hope This Helps You ❤️ANSWER :-
❥Fracking..!!!
Fracking is the process of drilling down into the earth before a high-pressure water mixture is directed at the rock to release the gas inside.
Hope it helps ya!❤
Please help. I’ll give brainliest.
Answer:
the third one is the one that you should pick
A. If you have a Periodic Table that is NOT color-coded describe where to look on the periodic table to to find elements which have similar chemical properties.
B. Explain why they have similar chemical properties.
C. Name three elements that have those similarities.
(I need a written paragraph please)
Answer:
Explanation:
A. Periodic table is beautifully arranged to place elements with similar chemical properties together. A family or a group is a vertical column in periodic table that has elements with similar property.
B. They all have similar properties because they all have the same number of valence electrons that determine the chemical properties such as reactivity of the element.
C. Lithium, sodium, potassium all fall in group 1 called alkali metals and these elements all share the property of being some of the most reactive elements.
How does reactivity vary when moving from left to right in third period of modern periodic table?
In the modern periodic table, reactivity increases when moving from left to right in the third period because metallic character decreases along a period.
The elements in the modern periodic table are arranged in 7 periods and 18 groups in a certain manner such that along a period , the metallic character of the element decreases and non-metallic character increases while on moving from top to bottom in a group, the metallic character increases and non-metallic character decreases.
The metallic character of elements depends upon its ability to lose electrons. Along a group, the size of atom increases and gradually the nuclear pull decreases so they can readily lose electrons but across a period, atomic size decreases and nuclear pull increases so they cannot lose electrons easily.
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What is the final temperature of a 93.9 g block of copper (whose specific heat is .385 J/g0C) that starts at a temperature of 45.0 degrees Celsius and absorbs 1,450.3 J of energy?
Answer:
7.01 hope this is right !
Explanation:
This problem can be summarized thusly:
qlost by copper = qgained by water + qgained by calorimeter
2) Therefore:
(610. g) (95.3 °C − x) (0.387 J g¯1 K¯1) = (45.0 g) (x − 36.5 °C) (4.184 J g¯1 °C¯1) + [(10.0 J/K) (x − 36.5 °C)]
Comment: The K and the °C cancel because the °C in this problem is a temperature difference (not one single specific value) and the "size" of one K = one °C.
22497.471 − 236.07x = 198.28x − 7237.22
424.35x = 29734.691
x = 70.1 °C
Calculate the volume of oxygen produced at STP from 172 grams of potassium chlorate, KClO3, in the following reaction:
KClO3 → KCl + O2 Show your work.
Answer:
64.2 L
Explanation:
In order to be able to calculate the volume of oxygen gas produced by this reaction, you need to know the conditions for pressure and temperature.
Since no mention of those conditions was made, I'll assume that the reaction takes place at STP, Standard Temperature and Pressure.
STP conditions are defined as a pressure of
100 kPa
and a temperature of
0
∘
C
. Under these conditions for pressure and temperature, one mole of any ideal gas occupies
22.7 L
- this is known as the molar volume of a gas at STP.
So, in order to find the volume of oxygen gas at STP, you need to know how many moles of oxygen are produced by this reaction.
Which two things affect how a lens refracts light?
Answer:
Explanation:
the correct answer is A
Answer:
hey hope this work
The amount of bending depends on two things: Change in speed – if a substance causes the light to speed up or slow down more, it will refract (bend) more. Angle of the incident ray – if the light is entering the substance at a greater angle, the amount of refraction will also be more noticeable.
and the answer i think is A
Cars are responsible for ____% of CO2 emissions. a10% b25% c100% d0%
Answer:
Explanation:
25%
The gas in a 250.0 mL piston experiences a change in pressure from 1.00 atm to 4.90 atm. What is the new volume (in mL) assuming the moles of gas and temperature are held constant
The gas in a 250.0 mL piston experiences a change in pressure from 1.00 atm to 4.90 atm. 56.2 ml is the new volume (in mL) assuming the moles of gas and temperature are held constant.
What is Boyle's law ?Boyle's law states that at a given temperature, the volume of a gas and its pressure are inversely proportional.
Robert A. Boyle discovered the law in 1662, which states that at a constant temperature, the volume of a gas is inversely proportional to the pressure exerted by the gas.
Given:
Initial volume (V₁) = 250 mL
Initial pressure (P₁) = 1.00 atm
Final volume (V₂) = ?
Final pressure (P₂) = 4.45 atm
Assuming the gas has an ideal behavior, we can find the final volume by using Boyle's law as follows:
P₁ × V₁ = P₂ × V₂
V₂ = P₁ × V₁/P₂
V₂ = 1.00 atm × 250 mL / 4.45 atm
V₂ = 56.2 ml
Thus, 56.2 ml is the new volume (in mL) assuming the moles of gas and temperature are held constant.
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When a hydrogen atom is part of a molecular structure, it is always a ___________ atom. Group of answer choices /-1 Central Terminal
When a hydrogen atom is part of a molecular structure, it is always a terminal atom.
On the periodic table, hydrogen belongs to the group 1 element. Consequently, a hydrogen molecule contains two valence electrons. There are two identical atoms in the H2 molecule. As a result, any atom can be regarded as a centre atom. An atom attached to a central atom is referred to as a terminal atom if it is not H. Here are two illustrations of this differentiation. Add bonding electrons to the total number of electrons. The end of hydrogen will never come. The centre will often contain the least electronegative element. Since hydrogen can only have two electrons in its valence shell and hence can only make one bond, it can never be the centre atom.
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Determine the empirical formula for each
compound.
a.
ethylene (C,H,)
b.
ascorbic acid (CH,O)
C.
naphthalene (CH)
Ethylene C2H2 , ascorbic acid formula C₆H₈O₆, naphthalene Chemical formula C₁₀H₈.
What the empirical formula tells us?The relative ratios of the various atoms in a compound are given by an empirical formula. The ratios are still valid at the molar level. H 2 O is made up of two hydrogen atoms and one oxygen atom. Similar to this, 1.0 mole of H2O is made up of 1.0 mole of oxygen and 2.0 moles of hydrogen.
What are the ascorbic acid ?Originally known as hexuronic acid, ascorbic acid is an organic molecule having the formula C 6H 8O 6. Although impure samples may appear yellowish, it is a white solid. Water readily dissolves it, resulting in moderately acidic solutions. It is a gentle reducer.
There are two enantiomers (mirror-image isomers) of ascorbic acid, generally referred to as "l" (for "levo") and "d." (for "dextro"). The most prevalent isomer is the l one, which is a naturally occurring form of vitamin C (also known as a "vitamer") and is necessary for both humans and many other animals to survive. Scurvy is caused by vitamin C deficiency and used to be a serious condition affecting sailors on lengthy sea trips. Due to its antioxidant qualities, it is utilized as a nutritional supplement and food additive.
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Use the following reaction: HI(g) ----à H2(g) + I2(g) a) Express the rate of reaction in terms of the change in concentration of each reactants & products. B) When [I2] is increasing at 2 mol/L-s, what is the rate as to how fast is [HI] decreasing? Show your relationships in your calculation set up for full credit. A)
a) The change in concentration of each reactant and product as a function of reaction rate is − Δ[H₂]/Δt = -Δ[I₂]/Δt = +1/2Δ[HI]/Δt.
b) The rate as to how fast is [HI] decreasing is 4 mol/[tex]L^{-s}[/tex].
An easy explanation of a chemical reaction.A chemical reaction is the process by which a single or more reactants change into a single or more new products. Chemical building blocks or compounds make up substances.
Given balance chemical reaction,
H₂(g) + I₂(g) → 2HI(g)
a) The rate of reaction in terms of the change in concentration of each reactants & products is
Rate = − Δ[H₂]/Δt = -Δ[I₂]/Δt = +1/2Δ[HI]/Δt
b) where 2, 1, 1 and stoichiometric coefficients of HI, H₂ and I₂ respectively.
where - sign indicates consumption and + ve sign indicates formation
given d[I₂]/dt =2
-d[HI]/2dt= 2
-d[HI]/dt = 4 mol/[tex]L^{-s}[/tex].
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Please balance this equation.
Answer:
C2H5OH + 3O2 → 2CO2 + 3H2O
Explanation:
Suppose that 20 mL of 2.50 x 10^-2 M aqueous H 2 SO 4 is required to neutralize 10.0 mL of an aqueous solution of KOH. What is the molarity of the KOH solution
The molarity of KOH solution will be 0.75 M.
The amount of moles of solute per liter of solution is known as molarity (M). Molarity is defined as moles of solute per liter of solution. To ascertain the concentration of an identified analyte, titration is a typical laboratory technique for quantitative chemical analysis. A standard solution with a known concentration and volume is prepared as the reagent, also known as the titrant or titrator.
The balanced equation is
[tex]H_{2} SO_{4}[/tex]+ 2KOH = [tex]2H_{2} O[/tex]+ [tex]K_{2} SO_{4}[/tex]
2.50 x [tex]10^{-2}[/tex] M= [tex]\frac{x}{0.2 L}[/tex]
So, 0.75 M KOH.
So, The molarity of KOH solution will be 0.75 M.
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what are the moon phases. but be more detailed and don't put in "the phases of the moon" in your own words.
In which of the following cases is the vapor pressure of ethanol greatest?
A. mole fraction of ethanol in water = 0.10
B. mole fraction of ethanol in water = 0.25
C. mole fraction of ethanol in water = 0.50
D. pure ethanol
Answer:
The answer Is c. mole fraction of ethanol in water=0.50
Explanation: