The silicate anion in the mineral kinoite is a chain of three `SiO_(4)` tetrahedra, that share corners with adjacent tetrahedra. The charge of silicate anion is

Options

A. `-4`
B. `-8`
C. `-6`
D. `-2`

Answer

To determine the charge of the silicate anion in the mineral kinoite, we will follow these steps:

### Step 1: Identify the Structure of the Silicate Anion
The silicate anion in kinoite consists of three `SiO4` tetrahedra that share corners. This means we have three silicon atoms and a certain number of oxygen atoms.

### Step 2: Count the Number of Silicon Atoms
Since there are three `SiO4` tetrahedra, we have:
- Number of silicon (Si) atoms = 3

### Step 3: Count the Number of Oxygen Atoms
Each `SiO4` tetrahedron contains 4 oxygen atoms. However, because the tetrahedra share corners, we need to calculate the total number of unique oxygen atoms:
- In a chain of three `SiO4` tetrahedra, the number of oxygen atoms can be calculated as follows:
- The first tetrahedron contributes 4 oxygen atoms.
- The second tetrahedron shares one oxygen atom with the first, contributing 3 new oxygen atoms.
- The third tetrahedron shares one oxygen atom with the second, contributing 3 new oxygen atoms.

Thus, the total number of oxygen atoms is:
- Total oxygen = 4 (from the first tetrahedron) + 3 (from the second) + 3 (from the third) = 10

### Step 4: Write the Formula for the Silicate Anion
From the above counts, we can write the formula for the silicate anion:
- The formula is `Si3O10`.

### Step 5: Calculate the Charge of the Silicate Anion
Now, we need to calculate the overall charge of the silicate anion:
- The charge contributed by oxygen: Each oxygen atom has a charge of -2.
- Therefore, for 10 oxygen atoms:
\[ \text{Charge from oxygen} = 10 \times (-2) = -20 \]

- The charge contributed by silicon: Each silicon atom has a charge of +4.
- Therefore, for 3 silicon atoms:
\[ \text{Charge from silicon} = 3 \times (+4) = +12 \]

### Step 6: Combine the Charges
Now, we combine the charges from silicon and oxygen to find the total charge of the silicate anion:
\[ \text{Total charge} = \text{Charge from oxygen} + \text{Charge from silicon} = -20 + 12 = -8 \]

### Conclusion
The charge of the silicate anion in the mineral kinoite is **-8**.

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