Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions. Phenolphthalein is slightly soluble in water and usually is dissolved in alcohols for use in experiments.
Answer:The molar mass of atoms of an element is given by the standard relative atomic mass of the element multiplied by the molar mass constant, 1 × 10−3 kg/mol = 1 g/mol.
Explanation:
n = m/M = 2/18 = 1/9 ~0,1 mol
Answer:
- <u>1. Equation: 2x + 3 = 9x - 11</u>
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- <u>2. Each row has 2 chairs</u>
Explanation:
The variable x represents the number of chairs in each row.
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<u>1. She can form 2 rows of a given length with 3 chairs left over.</u>
Thus, she has:
number of rows number of chairs in chairs number of chairs
each row left over she has
2 x 3 2x + 3
<u>2. She can form 9 rows of the same length if she gets 11 more chairs.</u>
That means that she is short in 11 chairs to have 9x chairs, or that she has 11 less chairs than 9x chairs. Then she has:
<u>3. Equation:</u>
Then, number of chairs she has is 2x + 3 and, also, 9x - 11, which allows to set the equation:
<u>4. Solve the equation:</u>
Therefore, each row has 2 chairs, and she has 2x + 3 = 4 + 3 = 7 chairs.
