help!!!
arrange the following binary hydrides in order of increasing melting points
CaH2, AIH3, NH3, GeH4, CH4
i don't understand how i cant figure it out
I suggest the easy way is to look up the melting points of each and arrange them. The most covalent should be the lowest and the most ionic should be the highest. Right off you figure CH4 is the most covalent and CaH2 is the most ionic. The others are between the high and low.
To arrange the binary hydrides in increasing order of melting points, we need to understand the factors that affect the melting points of compounds.
Melting points of binary hydrides can be influenced by several factors, including the type of bonding present (covalent or ionic) and the size and electronegativity of the elements involved.
In general, binary hydrides with more ionic bonding tend to have higher melting points than those with predominantly covalent bonding. Additionally, larger atoms or molecules tend to have weaker intermolecular forces and lower melting points.
Now, let's apply this information to the given binary hydrides:
1. CH4 (Methane) - Methane consists of carbon (C) and hydrogen (H) atoms. Since both carbon and hydrogen have similar electronegativity values, the bonding in methane is mostly covalent. As a result, methane has a relatively low melting point compared to other binary hydrides.
2. NH3 (Ammonia) - Ammonia consists of nitrogen (N) and hydrogen (H) atoms. Nitrogen is more electronegative than hydrogen, resulting in a polar covalent bond. While ammonia has some degree of covalency, it also exhibits a slight ionic character due to the electronegativity difference. As a result, ammonia has a slightly higher melting point compared to methane.
3. GeH4 (Germane) - Germane consists of germanium (Ge) and hydrogen (H) atoms. Germanium has a larger atomic size than nitrogen, and hydrogen and germanium have a smaller electronegativity difference compared to nitrogen-hydrogen. Therefore, GeH4 shows weaker intermolecular forces and has a lower melting point compared to ammonia.
4. AIH3 (Aluminum Hydride) - Aluminum hydride consists of aluminum (Al) and hydrogen (H) atoms. Aluminum has a higher electronegativity than germanium, resulting in a more polar covalent bond. The presence of higher electronegativity difference results in stronger intermolecular forces, leading to a higher melting point compared to germane.
5. CaH2 (Calcium Hydride) - Calcium hydride consists of calcium (Ca) and hydrogen (H) atoms. Calcium, being a metal, tends to form more ionic bonds with hydrogen. Therefore, CaH2 has the highest melting point among the given binary hydrides due to its predominantly ionic character.
So, based on the analysis, the binary hydrides arranged in increasing order of melting points would be:
CH4 < NH3 < GeH4 < AIH3 < CaH2