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3 years ago

Select all correct answers.

Chemistry

1 answer:

Jlenok [28]3 years ago

7 0

Answer: It showed that all atoms contain electrons.

Explanation:

J.J. Thomson's experiments inside a cathode ray tube in the presence of an electric field showed that all atoms contain tiny negatively charged subatomic particles "electrons".

Also, Thomson's plum pudding model of the atom had negatively-charged electrons embedded within a positively-charged "soup."

Furthermore, Rutherford's gold foil experiment showed that the atom is mostly empty space with a tiny positively-charged nucleus.

Then, Rutherford proposed the nuclear model of the atom based on these results.

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ASAP. Which pair of elements will form an ionic bond.

Bogdan [553]

4 because barium is ionic and chlorine is covelent

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3 years ago

B. What is the mass of a piece of wood that has a volume of<br> 25.3cm® and a density of 0.75g/cm?

fenix001 [56]

Answer:

Explanation:

$\frac{mass}{volume} =density\\mass=volume \times density=25.3 \times 0.75=18.975 ~gm$

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3 years ago

Why do some elements behave similarly? invoke atomic structure

vlabodo [156]

<span>The behavior, or reactivity, of elements in a group, or family will behave similarly because they have the same numbers of valence electrons. An example might be the alkali metals (with the exception of hydrogen, H, which is a gas) which form +1 ions in their compounds, have a relatively low melting point, and react violently with water. Other groups of atoms also show similar properties although different from the alkali metals. This type of behavior is one of the things that helps us categorize the elements into the periodic table of the elements. Mendeleev noticed similarities in the behavior of certain elements that originally allowed him to place them into families and develop that periodic chart</span>

6 0

3 years ago

In another experiment, the student titrated 50.0mL of 0.100MHC2H3O2 with 0.100MNaOH(aq) . Calculate the pH of the solution at th

Helen [10]

pH=8.87

<h3>Further explanation</h3>

Reaction

C₂H₄O₂+NaOH⇒CH₃COONa+H₂O

at the equivalence point = mol C₂H₄O₂= mol NaOH

mol C₂H₄O₂ : 50 x 0.1 = 0.5 mlmol=5.10⁻⁴ mol

The two reactants have completely reacted, and there is only salt(CH₃COONa) and water(H₂O), there will be hydrolysis

For acids from weak acids and strong bases (the solution is alkaline) then the calculation:

$\tt [OH^-]=\sqrt{\dfrac{Kw}{Ka}\times M }$

M=anion concentration=CH₃COO⁻

Ka=acid constant(for CH₃COOH,Ka=1.8.10⁻⁵)

$\tt [OH^-]=\sqrt{\dfrac{10^{-14}}{1.8.10^{-5}}\times 0.1 }$

$\tt [OH^-]=\sqrt{5.6.10^{-11}}=7.483\times 10^{-6}$

pOH=6-log 7.483=5.13

pH= 14 - 5.13=8.87

5 0

3 years ago

C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O (l)

vlabodo [156]

Answer:

Approximately $0.254\; \rm L$ (at STP.)

Assumption: both $\rm C_3H_8$ and $\rm CO_2$ act like ideal gases.

Explanation:

Make sure that this chemical equation is properly balanced.

The ratio between the coefficient of $\rm C_3H_8$ and that of $\rm CO_2$ is $1:3$ . As a result, for every $1\; \rm mol$ of $\rm C_3H_8$ consumed, $3\; \rm mol$ of $\rm CO_2$ will be produced.

In other words:

$\displaystyle \frac{n(\mathrm{C_3H_8\, (g)})}{n(\mathrm{CO_2\, (g)})} = \frac{1}{3}$ .

The coefficients in the balanced equation give a relationship between the number of moles of the two species. One more step is required to obtain a relationship between the volume of these two species.

Under the same pressure and temperature, two ideal gases with the same number of gas particles will have the same volume. Additionally, the volume of an ideal gas is proportional to the number of particles in it.

In this question, if both $\rm C_3H_8$ and $\rm CO_2$ are at STP, their pressure and temperature would indeed be the same. If they are both assumed to be ideal gases, then the ratio between their volumes would be the same as the ratio between the number of moles of their particles. that is:

$\displaystyle \frac{V(\mathrm{C_3H_8\, (g)})}{V(\mathrm{CO_2\, (g))}} = \frac{n(\mathrm{C_3H_8\, (g)})}{n(\mathrm{CO_2\, (g)})} = \frac{1}{3}$ .

Therefore, to produce $0.762\; \rm L$ of $\rm CO_2$ , the minimum volume of $\rm C_3H_8$ would be:

$\begin{aligned} &V(\mathrm{C_3H_8\, (g))} \\ &= \frac{V(\mathrm{C_3H_8\, (g)})}{V(\mathrm{CO_2\, (g))}} \cdot V(\mathrm{CO_2\, (g))} \\ &= \frac{1}{3} \times 0.762\; \rm L\end{aligned}$ .

3 0

3 years ago