Specific Rotation of R Enantiomer:
The specific rotation of a chiral compound is a property that describes the extent to which it rotates the plane of polarized light. It is denoted by the symbol [α]. In this case, the specific rotation of the R enantiomer is given as 48.

Specific Rotation of Sample with 25% S Enantiomer:
To determine the specific rotation of a sample that contains a mixture of the R and S enantiomers, we need to take into account the proportion of each enantiomer in the mixture. In this case, the sample contains 25% of the S enantiomer.

The specific rotation of a mixture of enantiomers can be calculated using the formula:

[α]mixture = ([α]R × %R) + ([α]S × %S)

where [α]mixture is the specific rotation of the mixture, [α]R is the specific rotation of the R enantiomer, [α]S is the specific rotation of the S enantiomer, %R is the percentage of the R enantiomer, and %S is the percentage of the S enantiomer.

Substituting the given values into the formula:

[α]mixture = (48 × 75%) + ([α]S × 25%)

Now, we need to solve for [α]mixture.

Since the specific rotation of the S enantiomer is not given, we cannot determine the exact specific rotation of the sample. However, we can make some observations based on the given information.

- The specific rotation of the R enantiomer is positive (+48).
- The specific rotation of the S enantiomer is expected to be negative (-α) because it is the enantiomer of the R enantiomer.
- The percentage of the S enantiomer is 25%.

Based on these observations, we can conclude that the specific rotation of the sample will be less than 48, but it will still be positive because the majority of the sample consists of the R enantiomer.

In conclusion, without knowing the exact specific rotation of the S enantiomer, we can determine that the specific rotation of the sample will be less than 48 and positive.