1) 7.15 * 10^6
since the exponent of the scientific notation is positive, move 6 places to the right.
so, <em>7.15 * 10^6 = 7150000</em>
2) 3.03 * 10^-8
Since the exponent of the scientific notation is negative, move the decimal point 8 places to the left.
so,<em> 3.03 * 10^-8 = 0.0000000303</em>
<em />
3)<em> </em>4.9 * 10^-1
since the exponent of the scientific notation is negative, move 1 decimal place to the left.
so,<em> 4.9 * 10^-1 = 0.49</em>
<em />
4) 2.886 * 10^5
since the exponent of the scientific notation is positive, move 5 decimal places to the right.
so,<em> 2.886 * 10^5 = 288600</em>
In a solution of KBr and water; KBr is the solute and water is the solvent;
Therefore; to achieve 3% by mass; it means we are going to have 3% of the mass being the solute and the other 97 % being the solvent.
Thus; KBr (solute) = 3/100 × 300 (total mass) = 9 g
Hence; the appropriate masses will be; 9.00 g of KBr and 291 g of water.
Balanced chemical equation:
2 H2 + 1 O2 = 2 H2O
4 g H2 -------> 32 g O2 -----------> 36 g H2O
↓ ↓ ↓
14.0 g ---------> 2.0 g O2 ----------> mass H2O ?
32 * mass H2O = 2.0 * 36
32 * mass H2O = 72
mass of H2O = 72 / 32
mass of H2O = 2.25 g
hope this helps!.
