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shusha [124]
3 years ago
15

A scientist compares two samples of white powder. one powder was present at the beginning of an experiment. the other powder was

present at the end. she wants to determine whether a chemical reaction has occurred. she finds that neither sample bubbles or dissolves in water. she measures the mass and volume of the solids. sample one has a volume of 45 cm3 and a mass of 0.5
g. sample two has a volume of 65 cm3 and a mass of 1.3
g. what should the scientist conclude?
Chemistry
2 answers:
NARA [144]3 years ago
8 0

Answer. Chemical reaction had occurred and both the powders are different substances.

Explanation:

As density is an intensive property of the substance.Which means that  different substance have different densities.

Density = \frac{mass}{volume}

Density of powder 1, d_1=\frac{0.5g}{45cm^3}=0.11g/cm^3

Density of powder 2, d_2=\frac{1.3g}{65cm^3}=0.02g/cm^3

On comparing both the densities of the powders we can say that both the substances are different. So we can conclude that the chemical reaction had occurred.

Masteriza [31]3 years ago
6 0
I think that the scientist should conclude that there was no chemical reaction. There were no clear evidences that a reaction had occurred. The variation in the volume and the mass was not an indication whether a reaction happened. Hope this answers the question. Have a nice day.
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10 points
daser333 [38]

In 1869 he published a table of the elements organized by increasing atomic mass.

Mendeleev is called the "father of the modern periodic table

stated that if the atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong. (He corrected the atomic masses of Be, In, and U)

was so confident in his table that he used it to predict the physical properties of three elements that were yet unknown.

After the discovery of these unknown elements between 1874 and 1885, and the fact that Mendeleev's predictions for Sc, Ga, and Ge were amazingly close to the actual values, his table was generally accepted.

However, in spite of Mendeleev's great achievement, problems arose when new elements were discovered and more accurate atomic weights determined.

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5 0
3 years ago
Read 2 more answers
An ionic bond forms when atoms blank electrons
8_murik_8 [283]

Answer:

An ionic bond forms when atoms transfer electrons.

Explanation:

Ionic bonds are formed when atoms transfer electrons. (In contrast, covalent bonds are formed when atoms share electrons.)

There's a distinction between the two: when two atoms react to form an ionic bond, one atom would completely lose one electron, while the other would completely gain that electron. The atom that loses the electron becomes a positively-charged ion called a cation, whereas the atom that gains the electron becomes a negatively-charged ion called an anion.

For example, consider the reaction between a sodium \rm Na atom and a chlorine \rm Cl atom: \rm Na + Cl \to NaCl.

When the sodium atom and the chlorine atom encounter, the sodium atom would lose one electron to form a positively-charged sodium ion, \rm Na^{+}. The chlorine atom would gain that electron to form a negatively-charged chlorine ion \rm Cl^{-}.

These two ions will readily attract each other because of the opposite electrostatic charges on them. This electrostatic attraction (between two ions of opposite charges) is an ionic bond.

Overall, it would appear as if the sodium \rm Na atom transferred an electron to the chlorine \rm Cl atom to form an ionic bond.

In contrast, when two atoms react to form a covalent bond, they share electrons without giving any away completely. Therefore, it is possible to break certain covalent bonds apart (using a beam of laser, for example) and obtain neutral atoms.

On the other hand, when an ionic bond was broken, the result would be two charged ions- not necessarily two neutral atoms. The electron transfer could not be reversed by simply breaking the bond.

For example, when table salt \rm NaCl is melted (at a very high temperature,) the ionic bond between the sodium ions and chloride ions would (mostly) be broken. However, doing so would only generate a mixture of \rm Na^{+} and \rm Cl^{-} ions- not sodium and chlorine atoms.

7 0
2 years ago
I need help with this please
jarptica [38.1K]

Answer: the place that i put the letters is how it should look also 75% of your peas are green

Explanation:

3 0
3 years ago
What changes if the degree (amount) of intermolecular bonds of a substance are changed?
elixir [45]
<h2>Answer:</h2>

The correct answers are;

volume of a substance

density of a substance

  • The volume and the density of the substance depend on inter molecular forces of the substance. So, when we will change the degree of inter molecular forces, whether decrease it or increase it, it will affect the volume and density of a substance.
7 0
3 years ago
Read 2 more answers
Consider the reaction: 2 H2O (g)--&gt;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
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