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oksano4ka [1.4K]
2 years ago
9

Why do scientist need government fundings?

Chemistry
2 answers:
Veseljchak [2.6K]2 years ago
8 0

Becuase they need special equipment and things like that that may not be available in the state i think

oksano4ka [1.4K]2 years ago
6 0
They need special equipment
You might be interested in
Lead(II) oxide from an ore can be reduced to elemental lead by heating in a furnace with carbon. Calculate the expected yield of
Lelu [443]

Answer:

53kg is the expected yield of lead

Explanation:

Firstly, in order to solve this question, we need to write the equation of reaction correctly. This is as follows:

PbO(s) + C(s) ---> Pb(l) + CO(g)

We proceed from here. We should get the limiting reactant but this can only be obtained by getting the number of moles of each reactant present.

The formula to use across all boards is that the number of moles is the mass of each of the reactant divided by the molar mass of each of the reactant.

For PBO, mass is 57kg = 57000g

Molar mass of PBO = 223.20g/mol

The number of moles is thus 57,000/223.2 = 255.37 moles

For carbon, mass is also 57kg = 57000g

Molar mass is 12g/mol

Number of moles of carbon = 57000/12 = 4750 moles

From the number of moles, we can see that the number of moles of Carbon is greater than that of PbO. This means that PbO is the limiting reagent.

Hence we use it to calculate percentage yield.

The number of moles of lead formed is the same of number of moles of lead oxide = 255.37 since we have mole ratio of 1 to 1

The molar mass of lead is 207.20g/mol

The mass of lead formed is = moles of lead formed * molar mass of lead = 207.20 * 255.37 = 52,912g which is approximately 53kg

Hence the expected yield is 53kg

6 0
3 years ago
State general trend for metal properties as you go left to right across a period
qwelly [4]

Periodic trends are specific patterns that are present in the periodic table that illustrate different aspects of a certain element, including its size and its electronic properties. Major periodic trends include: electronegativity, ionization energy, electron affinity, atomic radius, melting point, and metallic character. Periodic trends, arising from the arrangement of the periodic table, provide chemists with an invaluable tool to quickly predict an element's properties. These trends exist because of the similar atomic structure of the elements within their respective group families or periods, and because of the periodic nature of the elements.

Electronegativity Trends

Electronegativity can be understood as a chemical property describing an atom's ability to attract and bind with electrons. Because electronegativity is a qualitative property, there is no standardized method for calculating electronegativity. However, the most common scale for quantifying electronegativity is the Pauling scale (Table A2), named after the chemist Linus Pauling. The numbers assigned by the Pauling scale are dimensionless due to the qualitative nature of electronegativity. Electronegativity values for each element can be found on certain periodic tables. An example is provided below.


From left to right across a period of elements, electronegativity increases. If the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one. Conversely, if the valence shell is more than half full, it is easier to pull an electron into the valence shell than to donate one.

From top to bottom down a group, electronegativity decreases. This is because atomic number increases down a group, and thus there is an increased distance between the valence electrons and nucleus, or a greater atomic radius.

Important exceptions of the above rules include the noble gases, lanthanides, and actinides. The noble gases possess a complete valence shell and do not usually attract electrons. The lanthanides and actinides possess more complicated chemistry that does not generally follow any trends. Therefore, noble gases, lanthanides, and actinides do not have electronegativity values.

As for the transition metals, although they have electronegativity values, there is little variance among them across the period and up and down a group. This is because their metallic properties affect their ability to attract electrons as easily as the other elements.

According to these two general trends, the most electronegative element is fluorine, with 3.98 Pauling units.



6 0
3 years ago
A 20.00 ml sample of a solution of sr(oh)2 is titrated to the equivalence point with 40.03 ml of 0.1159 n hcl. what is the molar
goblinko [34]
The   molarity  of Sr(OH)2  solution is  =  0.1159 M

    calculation
write the equation  for reaction
that is,  Sr(OH)2 +2HCl→ SrCl2 + 2 H2O

then finds the mole  of HCl used

moles = molarity x volume 
=40.03 x0.1159 =  4.639 moles

by  use of mole ratio between Sr(OH)2 to  HCL which is 1 :2  the moles of Sr(OH)2  is therefore =  4.639  x1/2 = 2.312  moles

molarity  of  Sr(OH)2  is =  moles  / volume

=2.312 /20 =0.1159 M
3 0
3 years ago
Consider the reaction: 2 H2O (g)-->2 H2 (g) + O2 (g). ΔH=483.6 Kj/mol. If 2 moles of H2O (g) are converted H2(g) and O2(g) ag
denis-greek [22]
DE = dH - PdV 

<span>2 H2O(g) → 2 H2(g) + O2(g) </span>

<span>You can see that there are 2 moles of gas in the reactants and 3 moles of gas in the products. </span>

<span>1 moles of ideal gas occupies the same volume as 1 mole of any other ideal gas under the same conditions of temp and pressure. </span>

<span>Since it is done under constant temp and pressure that means the volume change will be equal to the volume of 1 mole of gas </span>

<span>2 moles reacts to form 3 moles </span>

<span>The gas equation is </span>

<span>PV = nRT </span>
<span>P = pressure </span>
<span>V = volume (unknown) </span>
<span>n = moles (1) </span>
<span>R = gas constant = 8.314 J K^-1 mol^-1 </span>
<span>- the gas constant is different for different units of temp and pressure (see wikki link) in this case temp and pressure are constant, and we want to put the result in an equation that has Joules in it, so we select 8.314 JK^-1mol^-1) </span>
<span>T = temp in Kelvin (kelvin = deg C + 273.15 </span>
<span>So T = 403.15 K </span>

<span>Now, you can see that PV is on one side of the equation, and we are looking to put PdV in our dE equation. So we can say </span>

<span>dE = dH -dnRT (because PV = nRT) </span>

<span>Also, since the gas constant is in the unit of Joules, we need to convert dH to Joules </span>

<span>dH = 483.6 kJ/mol = 483600 Joules/mol </span>

<span>dE = 483600 J/mol - (1.0 mol x 8.314 J mol^-1K-1 x 403.15 K) </span>
<span>dE = 483600 J/mol - 3351.77 J </span>
<span>dE = 480248.23 J/mol </span>
<span>dE = 480.2 kJ/mol </span>
5 0
3 years ago
Read 2 more answers
The base unit of measurement of liquids and volume.
Gemiola [76]

Answer:

Liters

Explanation:

3 0
3 years ago
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