The most common method astronomers use to determine the composition of stars, planets, and other objects is spectroscopy. This process utilizes instruments with a grating that spreads out the light from an object by wavelength. This spread-out light is called a spectrum. Every element has a unique fingerprint that allows researchers to determine what it is made of.

The fingerprint often appears as the absorption of light. Every atom has electrons, and these electrons like to stay in their lowest-energy levels. But when photons carrying energy hit an electron, they can push it to higher energy levels. This is absorption, and each element’s electrons absorb light at specific wavelengths related to the difference between energy levels in that atom. But the electrons want to return to their original levels, so they don’t hold onto the energy for long. When they emit the energy, they release photons with exactly the same wavelengths of light that were absorbed in the first place. An electron can release this light in any direction, so most of the light is emitted in directions away from our line of sight. Therefore, a dark line appears in the spectrum at that particular wavelength.

Because the wavelengths at which absorption lines occur are unique for each element, astronomers can measure the position of the lines to determine which elements are present in a target. The amount of light that is absorbed can also provide information about how much of each element is present.

5 0

2 years ago

Which is the correct net ionic equation for the following reaction: H3PO4 (aq) + 3 LiOH (aq) > Li3PO4 (aq) + 3 H2O (l)?

torisob [31]

Answer: The correct option for the chemical equation $H_3PO_4(aq.)+3LiOH(aq.)\rightarrow Li_3PO_4(aq.)+3H_2O(l)$ is 1.

The correct option for the chemical equation $2HBr(aq.)+Co(OH)_2(aq.)\rightarrow CoBr_2(aq.)+2H_2O(l)$ is 3.

Explanation:

For the chemical equation:

$H_3PO_4(aq.)+3LiOH(aq.)\rightarrow Li_3PO_4(aq.)+3H_2O(l)$

$H_3PO_4$ is a weak acid and hence will not dissociate into ions whereas LiOH is a strong base and will easily dissociate into ions.

The product $Li_3PO_4$ is soluble in water and hence, will dissociate into its respective ions. Hence, the ionic equation for this reaction is:

$H_3PO_4(aq.)+3Li^{3+}(aq.)+3OH^-(aq.)\rightarrow 3Li^{3+}(aq.)+PO_4^{3-}(aq.)+3H_2O(l)$

Net ionic equation becomes:

$H_3PO_4(aq.)+3OH^-(aq.)\rightarrow PO_4^{3-}(aq.)+3H_2O(l)$

So, the correct option is 1.

For the chemical equation:

$2HBr(aq.)+Co(OH)_2(aq.)\rightarrow CoBr_2(aq.)+2H_2O(l)$

HBr and $Co(OH)_2$ are strong acid and strong base respectively, hence they will easily dissociate into ions.

The product, $CoBr_2$ is is soluble in water and hence, will dissociate into its respective ions. Hence, the ionic equation for this reaction is:

$2H^+(aq.)+2Br^-(aq.)+Co^{2+}(aq.)+2OH^-(aq.)\rightarrow Co^{2+}(aq.)+2Br^-(aq.)+H_2O(l)$

The net ionic equation becomes:

$H^+(aq.)+OH^-(aq.)\rightarrow H_2O(l)$

So, the correct option is 3.

4 0

2 years ago

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