We can care for the pH meter electrode by;
1) Making sure that the electrode remains moist
2) The electrode should be stored in a 4M solution of KCl
3) Electrodes should not come in contact with deionized water.
What is pH?The term pH has to do with the negative logarithm of the hydrogen ion concentration. Now we know that the pH of a solution tells us the amount of the hydrogen ions or the hydroxyl ions that is present in the solution. The pH mete is the instrument that we could use to be able to measure the pH of the solution.
The pH scale runs between 0 - 14. The points on the scale that have been labeled from 0 - 6 tells us that the solution is an acidic solution and contains more hydrogen ions. If the solution has a pH of 7, then it is neutral and contains equal concentration of hydrogen and hydroxyl ions. A solution of pH 8 - 14 is basic and contains more hydroxyl than hydrogen ions.
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Provide the number of moles of Ca^ 2- ions contained in 0.125 L of 0.455 M solution of Ca 3 (PO 4 ) 2
Answer:
Moles of Ca3(PO4)2 = 0.455 M * 0.125 L = 0.0569 mol
1 Mole of Ca3(PO4)2 = 3 moles of Ca2+ ions
Thus, moles of Ca2+ ion = 3 * 0.0569 = 0.1707 ~ 0.171 moles
The number of moles of ions in a solution can be calculated using the molarity and volume of the solution. The number of moles of Ca ²⁺ ions contained in 0.125 L of 0.455 M solution of Ca₃ (PO₄) ₂ is 0.0170 moles.
What is molarity?Molarity is a term used to represent the concentration of the solution. Mathematically it is the ratio of number of moles of solute to the volume of solution in liters.
The molarity of the calcium phosphate solution is given 0.455 M and its volume is 0.125 L. Thus, the no.of moles of calcium phosphate in the solution is calculated as follows:
no.of moles of Ca₃ (PO₄) ₂ = molarity × volume
= 0.455 M × 0.125 L
= 0.0568 moles.
It is clear from the formula that one mole of calcium phosphate contains 3 moles of Ca ²⁺ ions. Therefore, the number of moles of calcium ions in 0.0568 moles of calcium phosphate is calculated as follows:
No. of moles of Ca ²⁺ ions = 0.0568 × 3
= 0.0170 moles.
Hence the number if moles of calcium ions in 0.125 L of 0.455 M calcium phosphate is 0.0170 moles.
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Can you please help me with 1-13
Answer:
E, C, A, 90, 5, D, B, D, D, D and B, A C and E, A, E
Explanation:
1. is correct, it is E
2. is C, not D. D is when the liquid is freezing/when the solid is melting.
3. the answer is A. B is when the gas is condensing or when the liquid is boiling.
4. 90 temperature units. This is the boiling point. Technically the substance can still condense below this point until 5 temperature units, or D, but ignore that.
5. 5 temperature units.
6. D, this is where the solid and liquids exchange states (ie melting/freezing)
7. B, this is where boiling and condensing occurs
8. Crystallisation is a fancy word for freezing. The melting and freezing points are the same, so D
9. D. Fusion means freezing.
10. D and B.
11. A, C, and E
12. A has the highest temperature and the highest kinetic and potential energy
13. E has the lowest kinetic and potential energy
What is the expected product from the reaction of potassium with oxygen?K2O2K2OKO2KO
Potassium oxide is an ionic compound formed by combining potassium and oxygen. It carries the chemical formula K2O.
So, this is expected product from the reaction of potassium with oxygen because of the following:
To get the net charge of the compound equal to zero, we need to satisfy the equation K2O. So that's the answer.
30.Which of the following procedures increases the amount of oxygen that is dissolved in a certain amount of water?Select one:a. Increasing the air pressure on the solution.b. Shaking the solution.c. Stirring the solution.d. Warming the solution.
Answer
a. Increasing the air pressure on the solution.
Explanation
What is the pH of a 0.83 M solution of sodium fluoride?
Report your answer to 2 decimal places.
The pH of a solution that is 0.67 M in sodium fluoride and 0.43 M in hydrofluoric acid is 8.53
What is the pH of a solution?The pH of a solution is the negative logarithm of the hydrogen ion concentration of the solution.
Mathematically:
pH = - log [H⁺]The pH of the given solution is calculated as follows:
Ka of HF = 7.2 * 10⁻⁴
Also, Kw = Ka * Kb
Kw = 1.0 * 10⁻¹⁴
Kb = 1.0 * 10⁻¹⁴ / 7.2 * 10⁻⁴
Kb = 1.39 x 10⁻¹¹
The [OH¯] is calculated using the Kb expression:
Kb = [OH⁻] * [H⁺] / [HA}
[OH⁻] = [H⁺] = x
Kb = x² / (0.83 - x)
Assuming x is negligible, the denominator = 0.83
x = √(1.39 x 10⁻¹¹ * 0.83)
x = 3.39 * 10⁻⁶
pOH = -log (3.39 * 10⁻⁶)
pOH = 5.47
pH = 14 - 5.47
pH = 8.53
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4 Fe(s) + 3 O2(g) → 2 Fe2O3(s) How many grams of oxygen gas, O2(g), are needed to react completely with 17.86 grams of iron?
• According to the balanced equation, we have :
4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)
4 x 55.85g of Fe reacts with 3 x 32g of Oxygen
Given 17.86 g of Ion, we want to find out how much oxygen will be required in this instance .
• So :
M.mass Fe: 4* 55.85 = 223.4
M.mass O2 : 3* 32 = 96
we can rearrange by :
223.4 → 96
17.86 → x .....(cross multiply )
223.4x = 96* 17.86
x = (96 *17.86) / 234.4
x = 7.314
• Therefore mass of oxygen required = 7.3g ,
195 ml of 0.355 m nacl is added to a 0.500 l volumetric flask and the flask is filled with water. calculate the [na⁺] concentration in the diluted solution.
Answer:
0.286 M
Explanation:
This is a great example of a practice problem that requires you to use the formula for dilution calculations.
To make it more interesting, let's assume that you're not familiar with that problem.
The most important thing to remember about a dilution is the the number of moles of solute must remain constant.
That is, the number of moles of solute present in the initial solution must be equal to the number of moles of solute present in the diluted solution.
Since molarity is defined as moles of solute per liter of solution, keeping the number of moles of solute constant allows you to decrease concentration by increasing the total volume of the solution.
195 ml of 0.355 ml NaCl is added to a 0.500 ml volumetric flask and the flask is filled with water. The [ Na⁺ ] concentration in the diluted solution is 138.45 M
What is concentration ?Concentration is calculated by dividing a constituent's abundance by the mixture's total volume. Mass concentration, molar concentration, number concentration, and volume concentration are four different categories of mathematical description.
Molarity is the number of moles of solute per liter of solution and mole fraction is the proportion of solute moles to all other moles of substances present. Parts per thousand grams, mass percentage, the ratio of the solute's mass to the solution's mass multiplied by 100.
M₁ V₁ = M₂ V₂
0.355 × 195 = M₂ × 0.500
M₂ = 0.355 × 195 ÷ 0.500
138.45 M
Thus, The [ Na⁺ ] concentration in the diluted solution is 138.45 M
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HELP ASAP 50 POINTS WILL MARK BRAINLY REAL ANSERS ONLY
Answer:A
Explanation:because i did the test
Component Q is more powerful in explaining a scientific phenomenon because peer conformation and support are characteristics of a theory.
Scientific phenomena are events that can be witnessed in the natural and artificial worlds that make people wonder and pose questions. A theory is a logical interpretation or explanation of a phenomenon or set of occurrences. For instance, the theory of evolution through natural selection is a hypothesis because it explains the variety of life on earth.
In addition to offering accurate explanations or interpretations, theories also serve additional objectives. Here, we examine three additional goals of theories: the organizing of well-understood phenomena, the forecasting of outcomes in novel circumstances, and the development of fresh lines of inquiry.
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Measurements show that the energy of a mixture of gaseous reactants decreases by 181.kj during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that -86.kj of work is done on the mixture during the reaction.
Calculate the change in enthalpy of the gas mixture during the reaction. Round your answer to 2 significant digits.
The change in enthalpy of the gas mixture during the reaction is - 95 kj.
The formula for the change in internal energy is given by:
ΔU = ΔH + W
ΔU = the change in inter energy = -181 kj ( decreased)
ΔH = the change in enthalpy
W = work done = -86 kj
substituting the values in the formula we get :
ΔU = ΔH + W
- 181 kj = ΔH - 86 kj
ΔH = -181 kj + 86 kj
ΔH = - 95 kj
Measurements show that the energy of a mixture of gaseous reactants decreases by 181.kj during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that -86.kj of work is done on the mixture during the reaction. The change in enthalpy of the gas mixture during the reaction is - 95 kj.
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How many moles of magnesium is 5.01 x 1022 atoms of magnesium?
Answer
Explanation
Note that a mole of any substance has 6.02 x 10²³ atoms of that substance.
Let x represent the mole of magnesium present in 5.01 x 10²² atoms of magnesium.
Therefore,
[tex]\begin{gathered} 1\text{ mole }=\text{6.02}\times10^{23}\text{ atoms} \\ x\text{ mole }=5.01\times10^{22}\text{ atoms} \\ \end{gathered}[/tex]Cross multiply, and divide both sides by 6.02 x 10²³ atoms to get x
[tex]undefined[/tex]
The reaction of carbon with oxygen to produce carbon monoxide is an example of which type (or class) of reaction?2C(s) + O2(g) → 2CO(g)single replacementendothermicdouble replacementcatalyticcombination
Combination. Option E is correct.
Explanations:Given the chemical reaction between carbon and oxygen expressed as:
[tex]2C(s)+O_2(g)\rightarrow2CO(g)[/tex]From the equation, you can see that carbn combines with oxygen atom to produce carbonmonoxide. This type of reaction is known as the combination reaction since it involves the reaction of two elements to produce a compound (carbon monoxide)
Based on the explanations above, we can concude that the reaction of carbon with oxygen to produce carbon monoxide is an example of a combination reaction.
What is the standard cell notation for an electrolytic cell with aluminum and gold electrodes? (answer choices in screenshot)
Oxidation takes place at the anode. Reduction takes place at the cathode. Oxidation takes place on the left and recution takes place on the right.
The standard cell notation for an electrolytic cell with alumium and gold electrodes:
[tex]Al(s)\lbrack Al^{3+}(aq)\parallel Au^+(aq)]Au(s)[/tex]To determine which metal undergoes oxidation and which undergoes reduction we use the standard cell potentetial of the metals. Au is the stronger oxidising agent of the two and so it is likely to undergo reduction and so the Al will undergo oxidation.
Answer: A
calculate the net force acting on the box in the following. refer to the screenshot below.
Answer:
6 N to the left, or -6 N
unbalanced
Explanation:
The forces are two 3 N forces. The forces are additive, so 3+3 = 6, so the answer is 6 N to the left.
Since the net force isn't 0, the forces are unbalanced (aka the block will move since there is a force pushing the block)
What is the name of the ionic compound CuBr
Answer:
Copper(I) bromide
Explanation:
Copper has oxidation numbers of +1 or +2
Bromide has a common charge of -1
This can be called Copper I bromide more precisely .or somewhat redudanately Copper mono bromide.
An older form of naming would be Cupous Bromide. Indicating a +1 charge on Copper. Cupric Bromide would be CuBr2 indicating a + 2 charge.
What does it mean for a strong base to be in equilibrium?
The position of equilibrium lies far to the right, with products being favored
O The position of equilibrium bes far to the left, with products being favored
There is a great deal of base and very few bns.
There is an equal amount of reactants and products.
The strong base to be in equilibrium refers to shifting towards the left side of the reaction and far away from the right side i.e option 1
What do you understand by equilibrium?
A system is at an equilibrium when all of its external forces are in balance.
Generally, In any acid-base reaction, the equilibrium will favor that side of reaction which moves the proton towards the stronger base.
Let us consider the given reaction
HCl (acid) + NaOH (strong base) NaCl + H20
As per the reaction, equilibrium will shift towards the left side as it involves the abstraction of the proton by the base.
Hence, the answer is option 1 first which means the position of equilibrium lies far to right.
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A student found that it required 25.8 mL of a 1.60 M NaOH solution to neutralize 15.0 mL of a certain H 2SO 4 solution which react according to the equation: 2 NaOH + H 2SO 4 → Na 2SO 4 + 2 H 2O. The molarity of the sulfuric acid solution
1) Check if the chemical reaction is balanced.
[tex]2NaOH+H_2SO_4=Na_2SO_4+2H_2O[/tex]2) Moles of NaOH in the reaction.
[tex]\text{Moles of NaOH =1.60 M}\cdot\frac{25.8\text{ mL}}{\square}\cdot\frac{1\text{ L}}{1000\text{ mL}}=\text{ 0.0413 moles of NaOH}[/tex]3) Moles of neutralized acid.
[tex]\text{Moles of H}_2SO_4\text{ =0.0413 moles of NaOH}\cdot\frac{1molesofH_2SO_4}{2\text{ moles of NaOH}}=0.0206molesofH_2SO_4[/tex]4) Molarity of H2SO4
[tex]\text{Molarity of H}_2SO_4=\frac{0.0206molesofH_2SO_4}{15.0\text{ mL}}\cdot\frac{1000\text{ mL}}{1\text{ L}}=1.38MH_2SO_4[/tex]Why is crystal of oxalic acid regarded as a primary standard solution ?
Answer:
dwn
Explanation:
Oxalic acid solution is a primary standard because it is highly pure, stable and does not change its concentration with environmental factors. > Coming to option B, Sodium thiosulphate, it is a secondary standard reagent. Sodium thiosulphate is also called hypo.
The atomic radius of a boron atom is 9 times 10-11m. Give its atomic radius in nanometres?
The atomic radius of boron atom is 0.09nm
What is an atomic radius?
Atomic radius, also known as atomic radii, is the total distance between an atom's nucleus and its electron's outermost orbital.
Atomic radius is thus defined as: The distance from the nucleus's center to the edge of its surrounding electron shells.
The radius of an atom is comparable to a circle's radius. The electron's most distant orbital is likened to the circle's outside edge, and the nucleus to the circle's center. The position of the outermost electron is unclear, making it challenging to calculate the atomic radii.
According to the question,
1m = 10-9nm
So, 9*10-11m = 0.09nm
The atomic radius of boron atom is 0.09nm
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Scientists can use chemicals to clean toxins from the soil. What does this
show about chemicals?
Any substance made of matter is by definition a chemical, which includes solids, liquids, and gases. Pure substances or mixtures of substances can both be found in chemicals. Water (H2O), for example, is a pure chemical because the same molecules and molecular combinations are present throughout its whole structure.
Explain about the chemicals ?Any material with a known composition is a chemical. Some chemicals, like water, are found in nature, meaning they always consist of the same "stuff." Other chemicals, including chlorine, are produced (used for bleaching fabrics or in swimming pools).
A chemical compound is a material that contains a specific combination of atoms or ions. Chemical compounds are made up of two or more elements coming together through a chemical process. While all substances are compounds, not all substances are compounds.
On its list of substances covered by the Toxic Substances Control Act, the EPA has more than 85,000 chemicals listed.
Not all chemicals are detrimental to the economy.
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A student conducts an experiment to determine how the temperature of water affects the time for sugar to dissolve. In each trial, the student uses a different amount of sugar and a different temperature of water. What is wrong with this experimental design? Responses The student needs to perform more trials. The student needs to perform more trials. The student does not have a dependent variable. The student does not have a dependent variable. The student changed too many variables. The student changed too many variables. The student did not change enough variables.
Answer:
The student changed too many variables.
This alkyl halide can be prepared by electrophilic addition of HBr to 2 different alkenes. Draw them
This alkyl halide can be prepared by electrophilic addition of HBr to 2 different alkenes because of alkenes undergo hydrogenation in presence of acid and base when HBr can added to the different alkyl 3-methyl-hex-2-ene, 3-methyl-hex-3-ene and 3-methylene hexane
Hydrogenation is the chemical reaction in which molecular hydrogen and another compound and element usually in presence of catalyst such as nickel, palladium or platinum and this process is commonly employed to reduce or saturated organic compound
Addition of hydrogen and halogen to the double bond or triple bond based on markovnikov rule of addition and when HBr is added to CH3- CH=CH2 then Br is added to CH group and H is added to the CH₂ group of the alkene and if the reaction is carried in the presence of any peroxide then reverse addition is taking place
Then different alkyl structure such as 3-methyl-hex-2-ene, 3-methyl-hex-3-ene and 3-methylene hexane and image is given below
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7.30×10² +2.80×10³
[? ] × 10²]
Scientific notation is the way that scientists handle large numbers and small numbers. For example, instead of writing 0.000 000 0056, they write 5.6 × 10⁻⁹.
We can think of 5.6 × 10⁻⁹ as the product of two numbers: 5.6 (the digits) and 10⁻⁹ (the power of 10).
Here are some examples of scientific notation.
1000 = 1 × 10³; 7354 = 7.354 × 10³
100 = 1 × 10²; 482 = 4.82 × 10²
10 = 1 × 10¹; 89 = 8.9 × 10¹
1 = 1 × 10⁰; 6 = 6 × 10⁰
1/10 = 0.1 = 1 × 10⁻¹; 0.32 = 3.2 × 10⁻¹
1/100 = 0.01 = 1 × 10⁻²; 0.053 = 5.3 × 10⁻²
1/1000 = 0.001 = 1 × 10⁻³; 0.0078 = 7.8 × 10⁻³
The exponent of 10 is the number of places we must shift the decimal point to get the scientific notation.
Each place the decimal moves to the left increases the exponent by 1.
Each place the decimal point moves to the right decreases the exponent by 1.
EXAMPLE:
Write the following numbers in scientific notation: 1001;
6 926 300 000; -392; 0.000 000 13; -0.0038
Solution:
1.001 × 10³; 6.9263 × 10⁹; -3.92 × 10²; 1.3 × 10⁻⁷; -3.8 × 10⁻³
Hope this helps!
Predict the chemical formula for the ionic compound formed by V³⁺ and NO₂⁻
You can see that NO₂⁻ has an oxidation number of -1 and V³⁺ has an oxidation number of +3.
When we state the chemical formula of these compounds, we need to have that the algebraic sum of the oxidation numbers must be zero. In this case, we have that the sum is -1 + 3 = 2, it is incorrect because we need to have the result of zero.
For this problem, we can multiply three times NO₂⁻ obtaining that the oxidation number is -3, so the algebraic sum would be: (-1)(3) + 3 = -3 + 3 = 0. This means that the chemical formula will have three times NO₂⁻ bonded with V³⁺ and it would be:
[tex]V(NO_2)_3.[/tex]How much work (in J ) is involved in a chemical reaction if the volume decreases from 4.25 to 1.97 L against a constant pressure of 0.838 atm ?
The amount of work (in J ) is involved in a chemical reaction if the volume decreases from 4.25 to 1.97 L against a constant pressure of 0.838 atm is: 8.78 Joules.
What is work done?The work done by an object can be calculated by multiplying the force acting on it by the perpendicular distance covered by the physical object. Also, the work done during a chemical reaction can be determined by multiplying the change in volume by the accompanying level of pressure.
Mathematically, the work done by a system is given by the formula:
Work done = PΔV = P(V₂ - V₁)
Where:
P represents the pressure.V represents the volume.Substituting the given parameters into the formula, we have;
Work done = 0.038(4.25 - 1.97)
Work done = 0.038(2.28)
Work done = 0.08664 L.atm
Next, we would convert L.atm to Joules:
Work done = 101.325 × 0.08664
Work done = 8.78 Joules.
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A liquid in the lab has a density of 1.24 g/cm³ . What is the mass in grams of 254 mL of the liquid? I dont know where to start when to convert because of the Activ app. I need help on how to answer this.
The mass in grams of the 254 mL of the liquid, given that it has a density of 1.24 g/cm³ is 314.96 grams
How to determine the mass of the liquidWe'll begin by listing the out the parameters obtained from the question. This is given below:
Density of liquid = 1.24 g/cm³Volume of liquid = 254 mL = 254 cm³Mass of liquid =?The mass of the liquid can be obtained as follow:
Density = mass / volume
Cross multiply
Mass = Density × Volume
Mass of liquid = 1.24 × 254
Mass of liquid = 314.96 grams
Thus, the mass of the liquid is 314.96 grams
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A population is a group of plants or animals of the same ______ that live in an area.
Answer:
Species. A population is a group of plants or animals of the same species that live in an area.
Gizmo Student exploration melting point
Every substance has a specific temperature range at which it changes from one phase (solid, liquid, or gas) to another.
Measure the melting, boiling, and/or sublimation points of several substances using a realistic melting point device to see what these phase changes appear like on a tiny scale.
Make assumptions about the relative potency of the forces binding these compounds together based on the transition points.
By placing a small amount of an organic solid into a capillary tube, attaching it to the thermometer's stem in the centre of a heating bath, and gradually heating the bath, one can ascertain the temperature at which melting starts and ends.
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What do you call a way of acquiring knowledge through experiment?
a.Academic method C.Scientific method
b.Experimental method d.Scientific notation
Answer:B
Explanation:
3. Calculate the equilibrium constant ( Ke ) for the reaction below if the equilibrium mixture for the reaction was found o contain [ H₂S ] 0.25 M. [ H₂ ] = 1 M , and [ S₂ ] -0.2 M. 2H₂S ( g ) 2H₂ ( g ) + S2 ( g )
The equilibrium constant relates the concentrations of the products and reactants in the chemical equilibrium. To calculate it we can apply the following equation.
For the reaction: aA + bB ---> cC + dD
Equlibrium constant (Ke) will be:
[tex]K=\frac{\lbrack C\rbrack^c\times\lbrack D\rbrack^d}{\lbrack A\rbrack^a\times\lbrack B\rbrack^b}[/tex]The letters in square brackets refer to the concentration raised to the respective coefficient. Now we replace the known values:
[tex]\begin{gathered} K=\text{ }\frac{\lbrack H_2\rbrack^2\times\lbrack S_2\rbrack^1}{\lbrack H_2S\rbrack^2} \\ K=\frac{\lbrack1M\rbrack^2\times\lbrack0.2M\rbrack^1}{\lbrack0.25M\rbrack^2} \\ K=\frac{1M^2\times0.2M}{0.0625M^2} \\ K=3.2M \end{gathered}[/tex]So, the equilibrium constant (Ke) will be 3.2M
Choose the words to finish the sentence.
The sinking of ocean crust back into the mantle when it meets continental crust is
Choose...
, and this occurs at
Choose...
.
The sinking of the ocean crust back into the mantle when it meets continental crust is referred to as subduction , and this process occurs at the ocean trenches.
What is Subduction?This is referred to as a geological process which occurs when there is collision between two tectonic plates in the earth in which one of the plate sinks into the mantle underneath the other plate.
During this process of subduction, the ocean crust sinks back into the mantle when it meets continental crust and it occurs mainly at the ocean trenches thereby making the options provided the correct choice.
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