28 a 20.0 ml sample of 0.15 m hydrochloric acid (hcl) is needed to neutralize a 10.0 ml sample of potassium…

28

Explanation:

Step1: Determine moles of HCl

Use the formula $n = M\times V$, where $n$ is moles, $M$ is molarity and $V$ is volume in liters. $V_{HCl}=20.0\ mL = 0.0200\ L$ and $M_{HCl}=0.15\ M$. So $n_{HCl}=M_{HCl}\times V_{HCl}=0.15\ mol/L\times0.0200\ L = 0.003\ mol$.

Step2: Use mole - ratio from balanced equation

From the balanced equation $HCl + KOH\rightarrow KCl + H_2O$, the mole - ratio of $HCl$ to $KOH$ is $1:1$. So $n_{KOH}=n_{HCl}=0.003\ mol$.

Step3: Calculate molarity of KOH

$V_{KOH}=10.0\ mL = 0.0100\ L$. Using the formula $M=\frac{n}{V}$, $M_{KOH}=\frac{n_{KOH}}{V_{KOH}}=\frac{0.003\ mol}{0.0100\ L}=0.30\ M$.

Answer:

B. 0.30 M

29

Explanation:

We need to balance the chemical equation for the reaction of titanium(IV) chloride ($TiCl_4$) with oxygen ($O_2$) to form titanium dioxide ($TiO_2$) and chlorine gas ($Cl_2$). For option A: The number of titanium atoms is 1 on both sides, the number of oxygen atoms is 2 on both sides and the number of chlorine atoms is 4 on both sides. For option B: The product should be $Cl_2$ not $4Cl$, so this is incorrect. For option C: The number of titanium atoms is not balanced (1 on left and 2 on right). For option D: The number of chlorine atoms is not balanced correctly.

Answer:

A. $TiCl_4 + O_2\rightarrow TiO_2+2Cl_2$