Why is an atom electrically neutral?

1 answer:

8 0

Electrons have electric charge of -1 and the number of electrons in an atom is equal to the number of protons. ... Heavier atoms tend to have more neutrons than protons, but the number of electrons in an atom is always equal to the number of protons. So an atom as a whole is electrically neutral.

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When 189.6 g of ethylene (C2H4) burns in oxygen to give carbon dioxide and water, how many grams of CO2 are formed?

BaLLatris [955]

Answer:

6.76

Explanation:

6 0

4 years ago

50.g of NaNO3 was dissolved in 1250 mL of water. what is the molality of the solution? [ Molar mass of NaNO3 = 85 g/mol

Viefleur [7K]

Answer:

Approximately $0.47\; \rm mol \cdot L^{-1}$ (note that $1\; \rm M = 1 \; \rm mol \cdot L^{-1}$ .)

Explanation:

The molarity of a solution gives the number of moles of solute in each unit volume of the solution. In this $\rm NaNO_3$ solution in water,

Let $n$ be the number of moles of the solute in the whole solution. Let $V$ represent the volume of that solution. The formula for the molarity $c$ of that solution is:

$\displaystyle c = \frac{n}{V}$ .

In this question, the volume of the solution is known to be $1250\; \rm mL$ . That's $1.250\; \rm L$ in standard units. What needs to be found is $n$ , the number of moles of $\rm NaNO_3$ in that solution.

The molar mass (formula mass) of a compound gives the mass of each mole of units of this compound. For example, the molar mass of $\rm NaNO_3$ is $85\; \rm g \cdot mol^{-1}$ means that the mass of one mole of

$\displaystyle n = \frac{m}{M}$ .

For this question,

$\begin{aligned}&n\left(\mathrm{NaNO_3}\right) \\ &= \frac{m\left(\mathrm{NaNO_3}\right)}{M\left(\mathrm{NaNO_3}\right)}\\&= \frac{50\; \rm g}{85\; \rm g \cdot mol^{-1}} \\& \approx 0.588235\; \rm mol\end{aligned}$ .