Answer:
Explanation:
The formula for calculating the enthalpy change of a reaction by using the enthalpies of formation of reactants and products is
TiCl₄(g) + 2H₂O(g) ⟶ TiO₂(s) + 4HCl(g)
ΔH°f/kJ·mol⁻¹: -763.2 -241.828 -939.7 -92.307
![\begin{array}{rcl}\Delta_{\text{r}}H^{\circ} & = & [-939.7 + 4(-92.307)] - [-763.2 + 2(-241.828)\\& = & [-939.7 - 369.228] - [-763.2 - 483.656]\\& = & -1308.928 + 1246.856\\& = & \mathbf{-62.1}\\\end{array}\\\text{The amount of heat evolved is } \boxed{\textbf{62.1 kJ}}](https://tex.z-dn.net/?f=%5Cbegin%7Barray%7D%7Brcl%7D%5CDelta_%7B%5Ctext%7Br%7D%7DH%5E%7B%5Ccirc%7D%20%26%20%3D%20%26%20%5B-939.7%20%2B%204%28-92.307%29%5D%20-%20%5B-763.2%20%2B%202%28-241.828%29%5C%5C%26%20%3D%20%26%20%5B-939.7%20-%20369.228%5D%20-%20%5B-763.2%20-%20483.656%5D%5C%5C%26%20%3D%20%26%20-1308.928%20%2B%201246.856%5C%5C%26%20%3D%20%26%20%5Cmathbf%7B-62.1%7D%5C%5C%5Cend%7Barray%7D%5C%5C%5Ctext%7BThe%20amount%20of%20heat%20evolved%20is%20%7D%20%5Cboxed%7B%5Ctextbf%7B62.1%20kJ%7D%7D)
Answer:
A carboxyl group (COOH) is a functional group consisting of a carbonyl group (C=O) with a hydroxyl group (O-H) attached to the same carbon atom. Carboxyl groups have the formula -C(=O)OH, usually written as -COOH or CO2H.
Answer:
A
Explanation:
To label an element correctly using a combination of the symbol, mass number and atomic number furnishes some important information about the element.
We can obtain these information from the element provided that correct labeling of the element is presented. Firstly, after writing the symbol of the element, the atomic number is placed as a subscript on the left while the mass number of the atomic mass is placed as a superscript on the same left.
Looking at the question asked, we have the element symbol in the correct position as Ca, with 42 also in the correct position which is the mass number. The third number which is 20 is thus the atomic number of the element.
