When performing a presumptive blood test with Hemastix, the reason why it necessary to test an unstained area close to the bloodstain under examination as a control is that the likelihood that there is presence of blood, and thus need confirmatory test in lab to know if it is actually blood.
What is the presumptive test for Hemastix?Hemastix reagent strips were initially created for the purpose of detecting blood in urine. It has been determined that this quick and simple test is useful as a presumptive test for the presence of blood.
Note that the presence of a chemical in a sample can be determined or confirmed using a presumptive test, which is a qualitative study. These decisions are typically made following a chemical reaction that results in the production of a certain color. A false positive occurs when a different chemical reacts similarly and yields the desired outcome.
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A block and tackle is a rope and pulley system that uses multiple pulleys. It multiplies a small force into a large one. If a motor has a weight of about 2500 N and people pull 4.0 m of rope with a force of 700 N to raise the motor 1.0 m, how efficient is the block and tackle?
The efficiency of the machine is obtained as 89.3%.
What is a pulley?A pulley is one of the types of simple machine. We know that a simple machine has to do with anything that helps you to be able to do your work more efficiently.
We know that the efficiency has to do with how well the pulley is able to do work as we know. In this case we know that the efficiency is obtained from;
Work output/Work input * 100/1
Work output =2500 N * 1.0 m = 2500 J
Work in put = 700 N * 4 m= 2800 J
Efficiency = 2500 J/2800 * 100/1
= 89.3%
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How many moles in 3.22 g of aluminum chloride?
3.22 g containing aluminum chloride contains 0.0241486951 moles, making 1 mole of an element's atoms weigh the same as its atomic mass in grams.
Why would one use aluminum chloride?Rubber, lubricants, wood preservers, and paints are all made in large part using aluminum chloride. In both medications and pesticides, it is utilized. while melting aluminum, as a flux Antiperspirant is how you apply it.
For what purpose does deodorant contain aluminum chloride?Cosmetic and pharmaceutical goods frequently contain aluminum compounds. The components that stop sweating in antiperspirants are aluminum salts. To prevent sweat from collecting on your pores' surface, the salts must dissolve.
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d. very polar compounds are sometimes purified by reverse phase chromatography where the stationary phase is very non-polar while the solvent is very polar. why would this technique be beneficial with extremely polar compounds?
very polar compounds are sometimes purified by reverse phase chromatography where the stationary phase is very non-polar while the solvent is very polar. this technique be beneficial with extremely polar compounds as it provides better solubility for the polar analytes.
The chromatography is the best technique to purified the organic compounds. if the stationary phase is polar it takes more times for polar molecule to absorbed in stationary phase. that's why we use reverse chromatography for the purified more polar compound.
Thus, very polar compounds are sometimes purified by reverse phase chromatography where the stationary phase is very non-polar while the solvent is very polar. this technique be beneficial with extremely polar compounds as it provides better solubility for the polar analytes.
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assume that you have produced the amount of 2-methylbenzoic acid from the previous question. what volume, in ml, of 6m naoh would you need to fully deprotonate the 2-methylbenzoic acid?
If we assume that you have produced the required amount of 2-methylbenzoic acid, then we would require 4.2 ml of 6m NaOH to completely deprotonate the 2-methylbenzoic acid.
Benzoic acid is more acidic than 2-methylbenzoic acid. because the +R (electron donating) nature of the methyl group causes the negative charge on the oxygen atom to become destabilized when the latter ions form 2 methyl benzoate ion. Consequently, it wouldn't have a propensity to emit H+.
An inorganic substance having the formula NaOH is sodium hydroxide, sometimes referred to as lye and caustic soda. Sodium cations and hydroxide anions make up this white solid ionic combination.
volume of 6 m NaOH = 6 1.8 = 4.2 ml.
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which fossil fuel can be made to burn cleaner and reduce carbon dioxide emissions if it is combined with purified oxygen?
Fossil fuel can be made to burn cleaner and reduce carbon dioxide emissions if it is combined with purified oxygen is coal.
Coal can be made to burn cleaner and reduce the carbon dioxide it it will combine with the purified oxygen. coal is type of fossil fuel. coal is black in color or brownish black. the fossil fuel coal is made up of plant. the plant gets their energy from the sunlight so, it is clear that col is from sun. fossil fuels are non renewable source of energy.
Thus, Fossil fuel can be made to burn cleaner and reduce carbon dioxide emissions if it is combined with purified oxygen is coal.
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how many coulombs are required to produce 77.0 g of lithium metal from a sample of molten lithium chloride?
1930 coulombs are required to produce 77.0 g of lithium metal from a sample of molten lithium chloride.
Weight of metal deposited = ECt / 96500, Applied charge= 1930C
Efficiency= 77%
Effective charge= 77/100 (1930)=1486.1C
96500C liberate 1 mole.
1447.5C liberates 1486.1 / 96500 moles = 0.0154 moles .
What is Molten lithium chloride ?LiCl-Li, a molten mixture of metallic lithium and lithium chloride, are crucial to the electrolytic reduction of a variety of metal oxides. Researchers have been studying these mixes' distinctive high temperature physical and chemical characteristics for decades.
Lithium metal is primarily made from lithium chloride by electrolyzing a LiCl/KCl melt at 450 °C (842 °F). LiCl is additionally employed in automotive parts as an aluminum brazing flux. As a desiccant, it dries out air streams.
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I WILL GIVE BRAINLY PLS HELP
Answer:
Ice wedging
Explanation:
The rocks crack fill with water and then expand
two unknown mineral samples, a and b, are rubbed against each other. mineral a scratches mineral b. what can you infer about the minerals?
Mineral A scratches mineral B, we can infer from here that Mineral A is more harder than Mineral B.
The minerals are the naturally occurring chemical compounds which are found in the earth's layers. Minerals have different properties.
If mineral A is rubbed against mineral B and Mineral A scratches mineral B, we can infer from here that the mineral A is harder than mineral B.
The hardness of the minerals is because of the intermolecular forces between the particles of the minerals. The mineral A might be having strong intermolecular forces in comparison with the mineral B.
This is why when rubbed against each other, the mineral A scratches the particle of the mineral B which has lower intermolecular forces between the particle of the mineral B.
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Complete question - Two unknown mineral samples, A and B, are rubbed against each other. Mineral A scratches mineral B. What can you infer about the minerals?
O Mineral A is harder than mineral B.
O Mineral B is harder than mineral A.
O Mineral A is more dense than mineral B
Mineral B is denser than mineral A.
what is the ph of a buffer with 0.462 m acetic acid and 0.355 m acetate. the ka for acetic acid is: 1.8 x 10-5
A buffer with 0.462 m acetic acid and 0.355 m acetate has a pH of 4.6. The acetic acid ka value is 1.8 x 10-5.
Buffer solution: What is it?The pH of a buffer solution won't change when small amounts of an acid or an alkali are added.
Simply put, a buffer solution that is acidic has a pH that is lower than 7. Acidic buffer solutions are normally made using a weak acid and one of its salts, frequently a sodium salt.
Alkaline buffer solution has pH higher than 7. The most common method for producing alkaline buffer solutions is to combine a weak base with one of its salts.
pH = -logKa + log([C₂H₃O₂⁻] / [HC₂H₃O₂])
ph = -log(1.8 × 10⁻⁵) + log(0.355 M / 0.462 M)
ph = 4.6
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calculate the temperature (in k) at which 0.0938 mol of o2 has a pressure of 740 torr in a 1.0l container.
The temperature (in k) will be 126.509 K
Number of moles of Oxygen = 0.0938 mol
Pressure = 740 torr or 98658.6 Pa
Volume = 1.0 L or 0.001 m3
Temperature in K = ?
To find out the temperature (T) we use the ideal gas equation
PV = nRT
As we have to find the temperature so rearrange the equation for T
T = PV / nR
value of R = 8.314 J/mol.K
Put the values in the equation
V = 98658.6 * 0.001 / 0.0938 * 8.314
V = 0.000974 / 0.779853
V = 98.6596 / 0.779853
V = 126.509 K
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2. what characteristic must the solvents in a liquid-liquid extraction solvent system share with one another?
In solvent extraction, we use two solvents. The important characteristic of extracting solvent is it should be immiscible with the second solvent.
What is solvent extraction and why is it important?
Solvent extraction also called liquid-liquid extraction (LLE) and partitioning, is a method to separate compounds based on their relative solubilities in two different immiscible liquids.The main purpose of solvent extraction is to isolate hazardous materials from the sediments and sludge or separate the useful components from debris.What are immiscible liquids?
Immiscible liquids are those which won't mix to give a single phase.
Oil and water are examples of immiscible liquids.
Thus, in liquid-liquid extraction, the two solvents should be immiscible with each other.
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a solution is prepared by dissolving 15.5 g of naoh in 1.50 l of solution. what is the molarity of this solution?
The molarity of a solution that is prepared by dissolving 15.5 g of NaOH in 1.50 L of solution is
How is molarity of solution calculated?The given values are,
volume = 1.50 L
weight of NaOH = 15.5 g
Mass NaOH= 40 g/mol
Therefore, moles of NaOH is = weight / mass
= 15.5 / 40
= 0.3875
We know,
Molarity= moles of NaOH / volume
= 0.3875 / 1.50
= 0.25833 M NaOH
Therefore, we get the molarity of this solution as 0.25833 M NaOH
What is molarity of a solution?Molarity is defined as the number of moles of solute dissolved in one liter of solution. Also called molarity and represented by the letter "M". Molarity formula M = n/v where M is the molarity n is the number of moles v is the total volume of the solution in liters.
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what is the molarity of an ethanol (c2h6o) solution that was prepared by dissolving 50.500 g of ethanol into water to a final volume of 750.0 ml? assume the solution has a density of 1.20 g/ml.
The molarity of the ethanol is 11.29M .
What is molarity ?
Molar concentration, also known as molarity, amount concentration, or substance concentration, is a unit used to describe the amount of a substance in a solution expressed as a percentage of its volume. The number of moles per litre, denoted by the unit symbol mol/L or mol/dm3 in SI units, is the most widely used unit for molarity in chemistry. One mol/L of a solution's concentration is referred to as one molar, or 1 M.
The mass of one mole of ethanol is 46.07 g/mol.
The number of mole in 50.500 g ethanol is 50.500/46.07 = 1.096158 mole.
We know that,
Mass = Density × Volume.
The final volume of the solution 750.0ml and the density of the solution is 1.20g/ml.
The mass of the solution is 1.20g/ml × 750.0ml = 900 gm.
The mass of water is (900-50.500) = 849.5 gm.
So the term molarity is defined as:
One of the most common units of concentration, expressed in M. It is defined as no moles of solute in 1 liter of solution.
The molarity of the solution is:
(1.09615 × 1000)/ 849.5 = 1.29M (approx.).
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Which property would cesium most likely have?
It is hard.
It is ductile.
It is a gas.
It has low reactivity.
Answer:
It is ductile.
Explanation:
Cesium belongs to group 1 on the periodic table, meaning it is an alkali metal, not a gas. Alkali metals are soft, malleable, and ductile. They are good conductors of heat and highly reactive in nature, meaning cesium is also highly reactive. Therefore, the only option that would make sense is "It is ductile."
what is the ph of a solution made by mixing 40.00 ml of 0.100 m hcl with 25.00 ml of 0.100 m koh? assume that the volumes of the solutions are additive.
The pH of the solution which was made by mixing 40ml of 0.100 M HCL with 25.00ml of 0.100 M KOH is 1.669.
The base and the acid have the same molarity, but the acid's volume is more than the bases' volume, hence after mixing the resultant solution is acidic.
The concentration of OH⁻ solution in the mixture is
= (molarity of base * volume of base - molarity of acid * volume of acid) / total volume
= (40 mL*0.1M - 25 mL *0.1 M ) / (40 mL +25mL)/ 1000)
= 0.021428571 M
pH = -log(0.021428571) = 1.669
Hence the pH is 1.669
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. at the beginning of his experiment, josh has 10 g of element a and 10 g or element b. when finished with the experiment, josh has 20 g of element a and b combined. this demonstrates what law?
josh has 10 g of element a and 10 g or element b. when finished with the experiment, josh has 20 g of element a and b combined. This demonstrates ' Law of conservation of mass'.
In a closed system, mass cannot be created or destroyed, but it can be changed from one form to another. Thus, mass of a system remains same before and after the reaction.
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How would switching to solar power affect a city environment?
The ability of solar energy to lower greenhouse gas emissions is the first and possibly most well-known advantage of this technology. This occurs as a result of solar energy as a coal energy substitute (the production of which harms the environment). Solar energy generation and consumption don't contribute to air pollution or the release of greenhouse gases.
As a result, making the simple effort to get in touch with local solar providers and switching to sustainable energy can have a significant long-term benefit.
Overall, switching to renewable energy will enable you to achieve your goals for sustainable living while also saving money. For instance, using solar energy lowers greenhouse gas emissions. Additionally, it prevents stress on the ecosystem and the world's water supply.
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hydroxide ion is a stronger nucleophile than either water or ethanol, yet the addition of koh during the kinetic runs in this experiment has virtually no effect on the reaction rates. explain.
catalytic process, A Ni catalyst is required for amide and alcohol to make the right esters. hydroxide ion is a stronger nucleophile than either water or ethanol,
In general, catalytic activity is a chemical interaction between a catalyst and a reactant that yields chemical intermediates more readily able to react with one another or with another reactant to yield the desired end product. Catalysis is the process of accelerating a chemical reaction by adding a catalyst to it. Catalysts are unaffected by and are not destroyed by the reaction.
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Does alcohol really burn off when cooking? what are the possible substitutions for alcohol in recipes?.
Answer:Does alcohol really burn off when cooking? what are the possible substitutions for alcohol in recipes?
Explanation:
The longer you cook, the more alcohol cooks out, but you have to cook food for about 3 hours to fully erase all traces of alcohol. A study from the U.S. Department of Agriculture's Nutrient Data lab confirmed this and added that food baked or simmered in alcohol for 15 minutes still retains 40 percent of the alcohol.
What can you say to the movie san andreas you've watch?
It appears that your answer contains either a link or inappropriate words. Please correct and submit again!
This is what it keeps saying when I want to answer so I have commented my answer below:
what is the concentration of hydroxide ions after 50.0 ml of 0.250 m naoh is added to 120 ml of 0.200 m na2so4? please show all work.
The concentration of the hydroxide ions after 50 ml of 0.250M NaOH is added to 120ml of 0.200M Na2SO4 is 7.35 x 10^-2 M.
What is meant by concentration?
Concentration is the total amount of solute present in the given volume of solution. this is expressed in terms of molarity, molality, mole fraction, normality etc. The term concentration mostly refers to the solvents and solutes present in the solution.
Concentration of hydroxide ions can be calculated by,
M (OH^-) = V (NaOH) x M (NaOH) / V (total) = 50ml x 0.250M / 50ml + 120ml = 0.0735M = 7.35 x 10^-2 M.
where M (OH^-) = concentration of hydroxide ions, V(NaOH) = volume of NaOH, M(NaOH) = concentration of NaOH.
Therefore, the concentration of the hydroxide ions after 50 ml of 0.250M NaOH is added to 120ml of 0.200M Na2SO4 is 7.35 x 10^-2 M.
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which group in the periodic table contains elements with the valence electron configuration of ns2np1?
group j neptunium Atomic number 93
24. what is the relationship between the number of bonds between two atoms and bond strength? bond length?
The strength of the bond describes how closely each atom is connected to another atom and how much energy is required to break that connection. The bond length is the average distance between the two atomic nuclei of two molecules that are joined together.
Define bond strength:The strength of the bond indicates how strongly each atom is bound to another and how much energy is expended in doing so. The force that a chemical bond utilizes to hold two atoms together is known as bond strength. The amount of energy required to break the bond is expressed in terms of the kilocalories per mole.
Define bond length:The equilibrium separation between the nuclei of two bound atoms in a molecule is referred to as the bond length. The bond length increases with increasing atom size. Bond multiplicity cause decrease in bond length. Rotational spectroscopy, X-ray diffraction, and other methods are used to measure it.
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Which atom’s ionization energy is greater than that of phosphorus (P)?
A) Ba
B) K
C) As
D) Cl
D.) CI
Explanation:Hi and Bye, have a good one. '^'
atoms from which of the following pairs are most likely to form an ionic bond? a) carbon and oxygen b) silicon and oxygen c) sodium and oxygen d) sulfur and oxygen
Atom pairs that are most likely to form an ionic bond is sodium and oxygen.
Thus, the correct option is C.
What is an ionic bond?А pаir of elements will most likely form аn ionic bond if one is а metаl аnd one is а nonmetаl. These types of ionic compounds аre composed of monаtomic cаtions аnd аnions. We cаn check the periodic tаble to see thаt the cаtions аre monаtomic ions formed from metаls, аnd the аnions аre monаtomic ions formed from nonmetаls.
Sodium is a metal, and oxygen is a nonmetal; therefore, [tex]N_{2} O[/tex] is expected to be ionic.
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Outline an alternative method and name equipment you could use to collect gas and work out the
volume produced in a more accurate way.
The alternative method to collect the gas and measure the volume is by a gas syringe.
What is a gas syringe?
Gas syringe is an equipment used to pump or withdraw gas from a closed container and can measure the volume of the gas produced in any chemical reaction.
The volume of the gas produced can be measured by reading the measuring scale on the gas syringe when the plunger moves in a gas syringe.
Hence, gas syringe is an alternative method to collect and measure the volume of the gas in a chemical reaction.
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an ideal gas sample has a certain volume at 350 k and 1 atm. the volume of the same sample at stp will be closest to the volume at 350 k and 1 atm multiplied by:
0.78 m³ is the volume of the same sample at standard temperature and pressure(stp) will be closest to the volume at 350 k and 1 atm.
What is ideal gas?The ideal gas law (PV = nRT) explains how the macroscopic properties of ideal gases are connected. The particles in an ideal gas are those that: (a) do not interact with one another; and (b) take up no space (have no volume). The ideal gas law does provide a good approximation of real gas behavior in many circumstances, but no gas is truly ideal.
PV = (nRT)
Where;
P₁ = initial pressure = 1 atm
V₁ = initial volume = 1 m³
T₁ = initial temperature = 350 k
P₂ = final pressure = 1 atm
V₂ = final volume = ?
T₂ = final temperature = 273 k
P₁V₁ / T₁ = P₂V₂ / T₂
Solving for V₂;
V₂ = P₁V₁T₂ / P₂T₁
V₂ = 1 × 1 × 273/350
V₂ = 273/350 m³
V₂ = 0.78 m³
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3. a student required 0.40 ml more naoh than she calculated she would need in question 1. explain how this might happen.
A student required 0.40 ml more NaOH than because it will use unstable indicator.
Chemical indicator, any substance which indicates visibly the existence or disappearance of a threshold concentration of such a chemical species, for instance an acid or a caustic in a solution, typically through a color change. One such chemical is methyl yellow, which gives an alkaline liquid a yellow color.
Indicators were weak acids as well as bases which exhibit a colour change when hydrogen ion quantity in a solution varies or as a solution's pH changes. In the water, the indicators gently separate to produce ions. Indicators include things like Litmus, turmeric, phenolphthalein, etc.
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Bond length. Need help solving with explanation I can understand please
The bond length or separation between the two nuclei of X in a molecule of X2A with elemental bond length of 2.22A and 4.28A is 6.5A.
What is bond length?
The bond length or bond distance can be defined as the average distance between the nuclei of the bonded atoms in the given molecule. If it is a polyatomic molecule the bond distance can be calculated by adding the atomic radius of all the atoms involved in bonding.
The separation or bond length of the molecule X2A can be calculated as,
The bond length of elemental A = 2.22A
The atomic radius of A = 2.22 / 2 = 1.11A
The bond of elemental X = 4.28A
The atomic radius of X = 4.28 / 2 = 2.14A
The bond length of molecule X2A = (2.14 + 1.11) x 2 = 6.5A.
Therefore, the bond length or separation between the atoms X in the given molecule is 6.5A.
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three atoms have the following ground state electron configurations. which statement regarding the atoms is true? atom 1: 1s22s22p63s23p2 atom 2: 1s22s22p63s23p5 atom 3: 1s22s22p63s23p64s1 group of answer choices g
Answer:
atom1:1s22s22p63s23p2