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miskamm [114]
3 years ago
6

Chromate is a polyatomic ion with a charge of negative two. it contains chromium and oxygen in a one-to-four ratio. what is its

formula?
Chemistry
1 answer:
mart [117]3 years ago
4 0
CrO_{4} ^{-2}

Because the ratio of the chromium to oxygen should be 1 is to 4, the first formula that comes to mind is CrO_{4} ^{-2}, with 1 chromium atom and 4 oxygen atoms.

The most common oxidation states of chromium are +6, +3, and +2. Less common are the oxidation states +5, +4, and +1 states, which are present in a few stable compounds. 

The oxide ion has a charge of -2. With the chromate formula being CrO_{4} ^{-2}, the chromium oxidation state (x) is calculated to be 

                            x + 4*(-2) = -2
                                        x  = -2+8
                                        x  = +6

The chromium oxidation state is +6, which is a known common oxidation state of chromium. 

Testing other 1:4 ratios of Cr and O by multiplying the ratio with different factors would give, 
 
               Cr_{2}O_{8} ^{-2}
               Cr_{3}O_{12} ^{-2}

and so on. 

Determining the oxidation state (x) of chromium for the two possible chromate ion formulas,

1.  Cr_{2}O_{8} ^{-2}

                          2x + 8*(-2) = -2
                                      2x  = -2+16
                                      2x  = +14
                                        x  = +7

2.  Cr_{3}O_{12} ^{-2}

                        3x + 12*(-2) = -2
                                      3x  = -2+24
                                      3x  = +22
                                        x  = +7.3

As observed, using chromate ion formulas in which the 1:4 ratio is multiplied by factors greater than 1, the calculated oxidation states of chromium are not  considered to be possible. Therefore, the only possible formula for the chromate ion with a chromium to oxygen ratio of 1:4, and an ionic charge of -2 is Cr O_{4}. 
. 
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When the equation Sn + HNO₃ → SnO₂ + NO₂ + H₂O is balanced in acidic solution, what is the smallest whole-number coefficient for
balu736 [363]

Answer:

1.

Explanation:

Hello,

In this case, for the given reaction we first assign the oxidation state for each species:

Sn^0 + H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 + N^{4+}O^{2-}_2 + H^+_2O^-

Whereas the half reactions are:

Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow  N^{4+}O^{2-}_2+H_2O

Next, we exchange the transferred electrons:

1\times(Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-)\\\\4\times (H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow  N^{4+}O^{2-}_2+H_2O)\\\\\\Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\4H^++4H^+N^{5+}O^{-2}_3 +4e^-\rightarrow  4N^{4+}O^{2-}_2+4H_2O

Afterwards, we add them to obtain:

Sn^0+2H_2O+4H^++4H^+N^{5+}O^{-2}_3  \rightarrow Sn^{4+}O_2 +4H^++4N^{4+}O^{2-}_2+4H_2O

By adding and subtracting common terms we obtain:

Sn^0+4H^+N^{5+}O^{-2}_3  \rightarrow Sn^{4+}O_2 +4N^{4+}O^{2-}_2+2H_2O

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Sn + 4HNO_3 \rightarrow SnO_2 + 4NO_2 + 2H_2O

Therefore, the smallest whole-number coefficient for Sn is 1.

Regards.

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12oz of water initially at 75oF is mixed with 20oz of water intiially at 140oF. What is the final temperature?
Kaylis [27]

Answer:

115.625^{\circ}\text{F}

Explanation:

m_1 = First mass of water = 12 oz

m_2 = Second mass of water = 20 oz

\Delta T_1 = Temperature difference of the solution with respect to the first mass of water = (T-75)^{\circ}\text{F}

\Delta T_2 = Temperature difference of the solution with respect to the second mass of water = (T-75)^{\circ}\text{F}

c = Specific heat of water

As heat gain and loss in the system is equal we have

m_1c\Delta T_1=m_2c\Delta T_2\\\Rightarrow m_1\Delta T_1=m_2\Delta T_2\\\Rightarrow 12(T-75)=20(140-T)\\\Rightarrow 12T-900=2800-20T\\\Rightarrow 12T+20T=2800+900\\\Rightarrow 32T=3700\\\Rightarrow T=\dfrac{3700}{32}\\\Rightarrow T=115.625^{\circ}\text{F}

The final temperature of the solution is 115.625^{\circ}\text{F}.

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Answer the following questions…
Zina [86]

The concentration of the hydronium ion in hydrochloric acid is 0.0045 M, and the pH of the solution is 2.34.

<h3>What is pH?</h3>

pH is the potential of the hydrogen or the hydronium ions in the aqueous solution.

As the solution contains 4.5 \times 10^{-3} \;\rm  M\; HCl the concentration of the hydronium ion will be the same, 4.5 \times 10^{-3} \;\rm  M.

The pH of the solution is calculated as:

\begin{aligned} \rm pH &= \rm -log[H^{+}]\\\\&= - \rm log (4.5 \times 10^{-3})\\\\&= 2.34\end{aligned}

The concentration of the hydroxide ion is calculated from pH and hydronium ion as:

\begin{aligned} \rm [H_{3}O^{+}][OH^{-}] &= 10^{-14}\\\\&= \dfrac{1 \times 10^{-14}}{4.5 \times 10^{-3}}\\\\&= 2.2 \times 10^{12}\end{aligned}

Now, for the calcium hydroxide solution, the calculations are shown as,

\begin{aligned} \rm (H_3}\rm O^{+}) &= \rm antilog (-pH)\\\\&= \rm antilog (-8)\\\\&= 10^{-8} \;\rm M\end{aligned}

pOH is calculated as:

\begin{aligned} \rm pOH &= 14- 8 = 6\\\\\rm [OH^{-}] &=  \rm antilog (-6)\\\\&= 10^{-6} \end{aligned}

The concentration of calcium hydroxide is calculated as:

\begin{aligned} &= \dfrac{1}{2} \times \rm [OH^{-}]\\\\&= 5 \times 10^{-4} \;\rm M\end{aligned}

Therefore, the pH and the pOH give the concentration of the hydrogen or the hydronium ion and the hydroxide ion.

Learn more about pH and pOH here:

brainly.com/question/16062632

#SPJ1

3 0
2 years ago
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